54Summary: Sirius hears Frank's story, and keeps it together just long enough to finally break down in private.
A/N: So...I cried writing the end of this chapter and decided I should probably just stop at that point, even though it's again shorter than before. So um. There's that. But I got it posted before New Year's so yay!
I didn't say this in last chapter's author's notes, but I think I should (a food for thought kinda thing). I personally don't believe the Longbottom attack was a coincidence. Both Harry and Neville were possible candidates for the prophecy, and Dumbledore had sent them both into hiding. I found it very interesting that just after the Potters kamikaze Voldemort, Bellatrix (who was apparently one of his top generals or whatever) and company go after the Longbottoms with a vengeance. I'd always believed that Riddle had planned to off both children - it's just good psycho murderer logic from where he stood - and he happened to choose to deal with Harry first. Maybe having Pettigrew on his side made Harry a bit more accessible than Neville, but I'm hard-pressed to believe that the man who'd wage war on infants just to prevent them from possibly growing up strong enough to defeat him would decide to off only one of them. I honestly always thought killing the Longbottoms was part of the plan and Bellatrix did it herself because Riddle had blown up. She's demented and devoted enough for it to be plausible.
.
.
The walk from the interrogation room to Frank's holding room wasn't too long, simply because having the holding cells near to the interrogation rooms was just good logistics when it came to moving suspects between the two.
That said, they still "happened" to come across no fewer than five other aurors on the way, all of whom had "duties" they were allegedly attending to, despite the fact that there wasn't currently anyone else using an interrogation room. Hopefully, Dunsmore had been able to keep them all away during the interrogation because besides the fact that aurors were terrible gossips, there were still a good number of them who were traitors and they didn't need to give the leaks any advance notice of what was to come. To that end, Bones and Taffle had agreed to keep mum about Sirius' position for a while longer yet as he put a few things in order.
When they got to the holding room, there was a short exchange between Bones and the auror who was standing guard at the door. Alan Mitchell was a common-born pureblood; a former Gryffindor, two or three years older than Sirius, and a good friend of Frank's. Though he and Sirius weren't close, they'd always been amiable and worked well together.
He'd been stony-faced and stiff as a board, apparently reluctant to let them past until Bones explained to him that Sirius had requested an interrogation room and had thoroughly proven his innocence. At her assurance, a bit of tension had eased from his posture, shoulders dropping a bit from his rigid stance.
He shot Sirius a look full of relief, tugging him into a brief hug and giving him a solid pat on the back.
"I didn't want to believe what everyone was saying - it didn't sound like you at all," he said, eyes sincere. "I'm glad I was right."
The other man would never know how much it meant to Sirius in that moment to hear someone who wasn't a Potter say something like that. To hear that there was someone, even if only one person, who truly didn't think him the kind of monster who'd have betrayed the family who'd taken him in and claimed him as their own...
(Someone who didn't believe that "once a Black, always a Black".)
There were no words to describe the sort of balm that was to his soul.
"Thanks, mate," Sirius said, after clearing his throat around the lump of sentiment that had formed. "But I need to see Frank."
The way Mitchell's expression dropped didn't fill Sirius with hope.
"Be honest - how bad is it?"
Mitchell let out a heavy breath - his cheeks puffing with the force of it - and ran a hand through his hair. The normally floppy brown locks were paradoxically both haphazard and limp, probably from him ruffling them in the way he often did when he was frustrated.
"It's...it's not looking good," he said finally. "When they first brought him in, he was basically incoherent. It was like he couldn't decide between being furious or broken. And he keeps saying he's cold, but he won't keep the cloak on; and he keeps looking around for Alice."
He dragged a hand down his face. Dread trickled down Sirius' spine - he and Mitchell were among the very few people left who knew that Frank hadn't had to actually search for Alice since the day they'd performed their marriage bond. That he kept doing it now was not looking good.
"I can't keep watching him realise she's not here," he said quietly, helplessly. "It's like watching him die a little more every time right in front of me."
Not for the first time in his life, Sirius sincerely wished that Bellatrix (and Walburga too, but he knew better than to ask for too much at once) would just drop dead. He didn't care how or where - he just wished she'd stop being a problem, and that would only happen if she was dead.
But he was the Regent, and he'd be throwing the weight of that behind Bones to clean up after this war. By hook or by crook, that witch would be sent through the veil before all was said and done, even if he had to toss her, hissing and spitting, through it himself.
Giving himself a mental shake and shelving the idea for later planning, he refocused on the wizard in front of him. "I still have to talk to him to find out what happened."
Mitchell shot him a considering look. He wouldn't know that Sirius was the Potter Regent, or the arrangement between Sirius, the Longbottoms, and the Potters. But he would know that Bones wouldn't have brought Sirius here at such a time unless it was utterly important.
The brunet sighed one last time and opened the door without another word.
When Sirius entered, he didn't even notice Flitwick staying outside with Bones and Taffle. When his eyes fell on Frank, there was a split second where all he processed was the fact that Frank was absolutely, undeniably alive.
And then he registered the actual state of Frank, and his relief was quite effectively quashed by the concern that raced through him instead.
The other wizard was wearing one of the cloaks kept on hand in the department for victims who were in shock, though it was just barely hanging on to one shoulder. But beneath it, Sirius realised that neat, proper Frank was still wearing a singed, ruined nightshirt that was more dust than cloth. His usually tidy brown hair was a mess, blood Sirius hoped wasn't his own crusting in it, along with what looked like rubble and grime. Oddly, the most concerning thing was the spectacular black eye forming below his oddly choppy fringe.
It was worrying because because Frank was very practical and usually dealt with any injuries as quickly as possible - said that he always needed to be fighting fit, even if he'd just come out of a scuffle. Having been raised by the formidable Augusta Longbottom, he was very professional at work, and would never have been caught dead going about in his nightshirt of all things besides. The only time Sirius had ever seen him remotely like this - a grand total of three times in the two years since Sirius had completed auror training! - had been because he was still so high-strung from a fight that he'd reflexively curse or hex anyone who got near to him. If they made the mistake of having a wand raised, even to attempt to heal him, it was one they never made again.
That the bruise was still doing its level best to swell his eye shut suggested that Frank was still too reactive for anyone to be able to attempt to heal it. It didn't bode well for whatever had happened with Bellatrix.
Before he could gather his wits enough to say anything, Frank broke the silence.
"Sirius?" he asked, attention snapping to the entering wizard. His good eye was a strange intersection of wild and sharp - like he was on the verge of going into shock, but it was sheer stubbornness that was keeping it at bay.
"What happened?" they both asked at the same time.
The ensuing confused pause didn't last long. Sirius wanted the night to be over, and he figured that the sooner they got Frank out of the DMLE, the better.
Sirius ushered them over to sit side by side on the cot in the room, and gave a very brief overview of what had happened on his end (heavily edited and short a few factoids that he'd prefer remained hidden for the moment). Frank was in no state to get all the details, but it seemed that hearing Sirius' pseudo-report helped ground him a bit more in the moment. Of course, Frank was just as incensed as Sirius was to discover Pettigrew's treachery - arguably more so since Pettigrew had also knowingly abandoned the Longbottoms to the attack he'd known was being planned.
(Privately, Sirius thought that, judging by the glint in Frank's eye, Pettigrew was very lucky that Sirius and Flitwick were the ones who'd caught him. Frank looked wild - bordering on manic - in a way Sirius had never seen him before, and he wasn't sure anyone would have been able to stop Frank taking his pound of flesh. Even if they'd gotten his wand away from him, Frank was built like a brick house and would have been able to do some serious damage before he was pulled off.)
There was a beat of silence and then Frank started speaking.
"We were in one of the lesser-known cottages that has been in the family for generations. Some great-grandcestor built it for his wife long before the statute, and we never remodeled it to get rid of some of the muggle things in it."
Sirius nodded to show he understood. Any building that old would have been built to accommodate muggles and squibs in the family, since they weren't taboo at the time. A lot of families who owned such properties had done away with the modifications after the Statute, when there was no longer a reason to cater to non-magicals in the family.
"We chose it because there was a tunnel from the nursery that let out somewhere outside the property wards, but it had its own, more stringent warding on both ends to only allow select persons in and out. We figured that if they got in somehow, we could escape through there."
It was a sound strategy, but obviously something went wrong somewhere.
"We didn't make it to the nursery," Frank said, his voice quiet and haunted. He stared straight ahead and Sirius could tell he was reliving it. "We were in the living room. Neville was exploring everything he could get his little hands on and then the property wards shuddered and buckled. We were trying to get to the nursery, but the wall exploded and then Bellatrix was in my house with the Lestranges and Crouch's spawn and it was all chaos."
Hands clenching and unclenching, Frank continued.
"Apparently," he said scornfully. "Barty found a way to trace our general location from my letter of leave to his father - and I still want to know how he even had access to official, confidential DMLE correspondence when he's not even an auror and such letters are never to leave Crouch's office in the DMLE. He wouldn't shut up about it actually; how the brilliant Ravenclaw outsmarted the dumb Gryffindors."
Guilt lanced though Sirius because he should have sent them a patronus when he arrived at the wreckage. Maybe if he had, Frank and Alice might have been a bit more on alert when they were attacked. Or even if he'd just been thinking during Pettigrew's interrogation. It was only when Skerritt had panicked afterwards that it had really registered to him that Pettigrew had confessed to knowledge of some sort of planned attack on Frank and Alice, but there'd been such a torrent of terrible information, it had just sort of gotten lost in the tide of it. Still, that sounded a paltry excuse for not having warned his friends earlier. And now they've suffered for it.
"They had us outnumbered," Frank continued, "and Alice was trying to shield Neville, but they separated us. Crouch kept going on about Elise-"
And Sirius recalled Frank's irritation about how crass Barty Crouch Jr. had been to his cousin after Benjy Fenwick had disappeared over the summer. Benjy and Elise had been courting, and with the way they'd been about each other, Frank had expected a proposal at some point in the future. Sometime prior to that, Elise had briefly entertained Crouch's attentions until she became uncomfortable for some reason and asked Frank to use his authority as the Patriarch of the family to officially veto a match between them just to keep him away. Benjy was an improvement in all respects, but then he disappeared and Crouch was suddenly harassing her all over again, despite having been vetoed and the fact that Elise had been very plain about having no intention to marry him and risk disownment, which was the whole point of a veto.
Suddenly, he remembered Pettigrew admitting that he'd helped set Benjy up for Crouch's initiation because Crouch had requested him specifically.
His stomach gave a lurch, but he decided that although he owed Frank that explanation, this wasn't the best time to give it.
And either way, Frank was still speaking.
"I felt when they broke Alice's shield," he said. "There was backlash in her magic and I felt her pain across the bond. As soon as it fell, Bellatrix cast crucio and then she was screaming."
He swallowed harshly, and one of the DMLE's house elves popped in to try to offer him a fresh glass of water, but Frank wasn't seeing her. Sirius took it in the hopes of forcing it on Frank when he was done and the little creature disappeared after shooting the wizard a concerned look.
"She screamed and screamed, and Neville was terrified and Bellatrix was cackling. I almost got past Rabastan, but then Crouch caught me in a Reprimo, so all I could do was watch."
He was shaking - hands clenched together in a futile effort to stop it. Sirius wasn't sure if it was from the chill Mitchell had mentioned, or fury at reliving the memory.
Sirius could empathise with the frustration. It figured Crouch would have taught his kid auror-level capture spells, and of course the little blighter would turn it on the auror he had a grudge against.
"Did you know the cruciatus hurts you by turning your own magic against your body?" the wizard asked him quietly. The question was redundant, since that was the whole reason the spell was considered dark. He still nodded silently, despite the fact that Frank wasn't looking at him. "Did you know that you can feel it across a marriage bond?" he asked, voice hoarse.
Sirius' gut swooped because that part was new.
"Because I didn't. Until tonight."
All was quiet for a few heartbeats, and Sirius didn't know how to breech it.
"And then your patronus came in, and everything froze as it gave your message. The way they all just stared at it in confusion would have been funny if I could have done anything about it," he said bitterly. "Crouch's spell even slipped a bit in his distraction. They all started laughing when it disappeared - found it so hilarious that the message had come too late. Bellatrix even stopped casting on Alice to cackle and gloat about it."
He took a fortifying breath and pressed on. "Alice was so still lying there, I'd have thought she and Neville were gone if I couldn't still feel their magic connected to mine. She'd been covering Neville with her body, so I couldn't see him. And he wasn't screaming anymore, but I could still feel his terror. And then while the lot of them were distracted, Alice - she -"
Sirius finally leaned over to touch their shoulders in support. He still wasn't sure how much Frank would welcome any contact at the moment, but he couldn't just leave his friend floundering like this.
Frank swallowed and continued, in a voice that was barely above a whisper. "She apologised. Across our bond. She was too exhausted to do anything physically, and she'd already screamed herself hoarse by that point anyway, but communicating through the bond was like breathing for us. She said she couldn't keep letting Bellatrix use her to hurt Neville and me through our bonds."
There was a slight movement and Sirius realised that Frank was fiddling with the band on his left ring finger. It was a nervous tick that few knew he had, and he'd only developed it after he and Alice had married. As far as Sirius could tell, the golden band that had manifested as a physical symbol of their magical union didn't feel any different to the rest of his friend's skin, but Frank sometimes traced it absently, particularly when he was missing Alice.
One glance at the now red band, however, and Sirius knew precisely where Frank's tale was heading, even if he wished with every fibre of his being that he was wrong.
"Before she said it, I didn't realise that it was bleeding over to Neville too. I didn't even have a chance to think about it - she told me she loved me and then her occlumency shields went up. We never do that - it feels wrong, like we're hiding from ourselves, or we've cut off half our senses," Frank said, voice distraught.
"She broke the bond from her end - even cut herself off from being the Holder."
Frank swallowed again, and Sirius pressed the glass on him. He stared at it for a moment, but eventually took it. He knocked it back like he wished it were something stronger, but it seemed to push him to be able to continue.
"Everyone knows the old wives' tales about Family Magic acting in defence of someone - and I've actually read an account or two where it happened in our Dyrne Stær."
Sirius blinked at the apparent non-sequitur.
"I've never Carried the Family Magic; Mother did it before Alice. And it-...we were furious. She gave it up somehow and it all rushed over to me. I just - I lost it. It felt so good to slice Crouch's head off after everything he'd had to say about Elise and Benjy. He was really happy to tell me all the different ways he'd tortured Benjy before he killed him, but he was begging by the time we finished with him too."
His lips quirked up in something a bit too bloodthirsty to really be called a smile.
"Rabastan was too slow to dodge the piercing charm to his forehead, and Rodolphus quite literally couldn't conjure a shield to save his life," he said, expression scrunching with disdain.
Sirius could empathise. From all accounts, while Bellatrix's reputation as a terrifying duellist was well-earned, the Lestrange brothers were only slightly above average. He wasn't sure what Barty's skill level was, since he was apparently a new recruit and hadn't had much of a chance yet to be public about his activities, but considering who his father was, he was quite likely decently skilled. But in Frank's defense, anyone would be hampered by trying to protect hostages while trying to capture their assailants alive. Immobilising someone as skilled as Frank early on was a sound strategy to take him out of the fight. It wouldn't hurt that it let them torture his family while he was helpless to stop them.
"We destroyed Bellatrix's wand arm," he said, something darkly satisfied in his voice bringing Sirius back to the moment.
He blinked in mild surprise, but he wouldn't judge because, to be fair, the witch had it coming.
"The cruciatus didn't phase her - she actually seemed to enjoy it," Frank told him, face scrunched in something like disgust.
Sirius' expression deadpanned, and it took every effort not to roll his eyes skyward because honestly? It was just par for the coarse at this point that Bellatrix would be the only person alive who would actually like being subjected to a pain curse. The Black brilliance had always been strong in her, but unfortunately for everyone around her, the Black Madness was winning the fight for dominance.
(In short, Bellatrix was as insane as she was intelligent, and Sirius still wondered whose bright idea it had been to arm her with a wand and let her loose on the rest of the world.)
"She actually managed to throw a hex at me while she was under it."
Which was impressive all on its own, but that was overshadowed by how horrifying it was that Bellatrix could function through such an incapacitating spell. He'd never heard of anyone else who could push past a crucio.
"But physical pain -" Frank said, vindictive satisfaction returning. "Physical pain still got to her just like anyone else. We could have severed her arm like we did for Crouch's head, and we wanted to - Merlin's beard we wanted to - but we wanted her to suffer first. And beside that, I needed at least one of them alive to interrogate later and the other three were already dead. But dammit it all we were owed for her attack on our Holder and Heir and we were taking our pound of flesh."
No one would argue that point. A Holder essentially carried the bulk of the legacy of a Family, so attacking them was understandably a grave offence. Killing that person wouldn't destroy the Family Magic, and may not even necessarily harm it, but it was the symbolism of it that mattered. It was as good as saying you wanted to destroy the Family completely - past, present, and future. Such attacks in times past had been grounds to declare a blood feud, whether or not the attacker had known for sure that the person was the Holder. In each of the few instances that it had sparked a blood feud, one or both of the Families involved had been completely wiped out.
"It took a petrification and a few bludgeoning curses, but we eventually got her arm off to the shoulder," Frank told him, almost conversationally. "Since we couldn't let her die yet, we cauterised it."
He looked quite a bit like he wished that last part wasn't necessary, but it couldn't be helped. It was well-known that Bellatrix was rather high up in You-Know-Who's chain of command, so she was undoubtedly a treasure trove of useful information.
Frank looked down at his hands and flexed the knuckles of his right, which Sirius only now realised was bruised. "She only finally shut up when I broke her jaw. That part was all me," he said with satisfaction.
Sirius let himself feel a bit (okay very) smug at the fact that she was finally caught, and there'd be no way for her to wriggle her way out of being executed for her crimes. He'd make doubly sure of it, for all the victims and broken people and families she'd left in her wake.
He turned and made sure that Frank was looking directly at him with his good eye. "Well whatever happens, she won't be getting away from justice this time. I swear it."
He didn't push any magic into the vow, but he didn't need to with what Frank knew of his new circumstances.
"Let them fix you up, and then go back to Neville," Sirius told him, pretending not to notice the way Frank's breath skipped. "He needs you right now, and it may do you some good. I know I wish had Harry in front of me, and your bond to Neville is deeper than I'd have let mine get to Harry before this mess."
"Neville," Frank breathed with a shudder. "I have - Neville - they - Mother took him - but he - Sirius I have to get to Neville!"
Frank shot to his feet, and then stumbled, probably due to some injury Sirius hadn't yet noticed. The younger wizard reached out a hand to steady the suddenly frantic man, and pulled him with some difficulty back to sitting on the cot.
He didn't blame Frank for the slip in his memory. Sirius could infer that Augusta had probably swept in and taken charge of things with Frank half-feral as he probably was. At any rate, she definitely wouldn't let any harm come to her grandson, and even scattered as he was, Frank would know it. Frank himself likely wouldn't be in a fit state to care for his son on his own for at least a few days anyway - a broken bond was reportedly awful to suffer through, and was another reason people tended not to undertake them in the first place.
Either way, Neville was definitely safer with Augusta than Harry was with Dumbledore, Sirius thought bitterly. He needed to investigate that thoroughly, but he was aware enough after Mistress Eigyr's particular brand of tough love that he'd botch it if he tried to do anything right this moment. He needed to plan properly to get the truth about just exactly what the hell the man had been thinking dumping Harry with Petunia in the middle of the night on Samhain.
It took a bit of coaxing to get Frank to agree to see a healer, but Sirius wasn't above using the threat that seeing him that way might scare little Nev even more to get him to cooperate.
The fact that one of the department's medi-wix came bustling in without Sirius having to send for them confirmed to him that someone was listening from outside. That wasn't surprising, because things said in these holding rooms could be used in cases with the right circumstances and permissions.
Once Frank had been prodded as much as he would tolerate, Sirius saw him to a floo. He was calmer now, but that didn't mean he'd be comfortable without someone he trusted at his back so soon after being attacked in his own home and losing Alice.
Both Bones and Taffle saw him and Flitwick off at the floos as well, since they'd come as well to see Frank off.
"I'll look into what we discussed, Professor," Bones was saying to Flitwick. "It is in fact all very suspicious, given everything else. And thank you for identifying the bodies and effects."
A jolt of surprise had Sirius turning wide eyes on them both. "What?" he asked in a strangled voice.
Bones shot him a sympathetic look. She remembered being the one to have to come in to claim the bodies of her brother and his family because everyone else was too distraught. She was as well; she was just better at masking it. Edgar had always had a special place in her heart as her baby brother, and what people had labelled "The Bones Family Massacre" had rocked her terribly.
It was no secret that James Potter and Sirius Black were as close as brothers. To be perfectly honest, despite the fact that Potter wasn't an auror, she'd still had to deal with enough shenanigans and tales to be convinced that the two men shared half a brain and regularly forgot it on Lily's dining table. But if the rumours regarding Black's running away from home, despite being the Heir were true, taken with the widely known fact that Charlus and Dorea Potter had granted him Sanctuary, it wasn't very surprising that they were so tightly knit.
She could see that Black's calmness was a façade, but only because she'd been there herself. If she could spare him having to see his family's dead bodies (again, since he'd mentioned being the one to find them in his account), she'd do it. He'd have enough hurdles to face in the coming months (and years, honestly) without adding this to it.
"While you were talking to Frank, I asked Professor Flitwick to formally identify and claim the bodies. Frank was too distraught to be asked to do it when he first came in, and the professor's relationship to them as expressed in their wills is adequate for what was needed."
"A few other topics of interest came up, but we can discuss them later," Flitwick put in, the lilt of his tone suggesting that whatever these new topics were, it was highly unlikely they were a good interesting.
He knew he should try harder to find out - wasn't that his job now as Regent? - but he just heaved an internal sigh instead. The weight of everything was beginning to press down on him again now that the scare with Frank had been dealt with (as much as it could be at this point). At the moment, he just wanted to stop and not have to think about anything - his dead friends, his sudden parenthood, his orphaned godson - sorry, son - the unknown witch, his new workload as Regent...
It was all too much at the moment, and he felt oddly fragile in a way he hadn't in years.
He made his goodbyes without any conscious knowledge of what he was saying, and the next time he was really aware, Skerritt's odd little house elf - what was her name again? Spice? Salt? - was tugging a warm blanket around his shoulders and settling a lovely smelling mug of tea in his hands. He was sitting in a comfortable chair in the bedroom Mistress Eigyr had provided for him to use.
"You be sitting here and resting," she was saying quietly. "Pepper be keeping watch over baby Master Harry and Missy Helen. We be safe behind Teacher Mistress' wards, but Pepper be guarding them anyway. Pepper be guarding you too."
He stared at her for a few moments, his mind feeling at once sluggish and like it would never shut up. She held his gaze with large purple eyes, and he read only sincere concern in them.
(But what did he know about reading people? Look how well that had turned out last time.)
"Why do you care?" he asked tiredly. There were any number of ways to interpret it, but she seemed to pick up what he really meant.
"Because you be needing us. Missy Helen and Teacher Mistress be bleeding hearts-"
Sirius raised an eyebrow at that, and she smiled.
"Teacher Mistress be tough bleeding heart, but she still be caring. She not be helping and letting you stay if she be over-caring about coming wix trouble. You and baby Master Harry be family now, and we always be protecting family."
Something in his heart clenched painfully at her words, and tears sprang unbidden to his eyes.
Family.
Before yesterday, there were a handful of people on this entire planet he would have applied that word to, and last night, he'd lost three of them. He wasn't sure how he'd ever get over Worm-Pettigrew's betrayal, but he'd have to. For Harry.
And now, here was this little elf, bright-eyed and kind like Lily was, claiming him after knowing him for only a day.
Part of him wanted to fight and rail that these strangers couldn't replace his family. No one could.
But the other part wanted to sob at the reminder of when Dad and Mum-Dorea took him in. They'd said something similar back then too.
Suddenly, the enormity of everything he'd lost and been suddenly thrust into came down on him and the tears spilled over. He took a shuddering breath in an effort to calm himself, and grew more upset when he found it wasn't working.
"Pepper be spelling privacy, Master Black. You be allowed to grieve and Pepper not be telling a soul."
And just like that, between one breath and the next, he was sobbing. Great, heaving things that left him shaking, hands clutching at his hair, his face, whatever he could reach. He didn't know where the mug had gone or when it had disappeared, but the elf stayed with him through the night, a silent vigil and support.
.
.
A/N: I swear this is supposed to be a happy fix-it fic, but I think Sirius deserved to be able to grieve that way he was never allowed to in canon. Not exactly a happy point to end the year, but maybe a mentally healthy one for Sirius? Idk. I promise things get better for him though. I'm not actually a fan of angst, but I like treating the characters like real people with feelings and emotions, and that means, they won't be happy all the time, but that makes them a bit more realistic, doesn't it?
I don't know legal process with claiming bodies or cleaning up after a murder or any of that stuff for any country anywhere, including my own. If anything there seems unrealistic to you, please suspend your disbelief and accept "magic changes things" as my excuse. I'm writing a fanfiction after all.
Bellatrix strikes me as both a sadist and a masochist all in one. She may not necessarily always derive sexual pleasure from pain (whether her own or someone else's), but she enjoys it all the same. For the purposes of this fic, she specifically enjoys magical pain as opposed to physical, which I think is reasonable considering. Just like some persons may revel in causing emotional pain over physical as well. I honestly don't envision her as a sexual creature. She's hailed as beautiful, which is totally fine, but there was nothing sensual about her. None of the soft edges I consider necessary for intimacy. Bellatrix had a whole husband and no children, in a society and social class that I think would have expected (low-key required) it of the union. She was demonstratively lusting after another man despite her marriage. I feel like everyone can agree that she never loved or cared for Rodolphus. I dunno why they got married, but it definitely wasn't love. She's attracted to power, but not necessarily sexually so.
Did anyone else notice Frank kept referring to "we" and "us"? I'm not sure it'd make sense to expound on it in the actual fic, so I'll just drop it here. It wasn't an accident. He was acting with the Longbottom Family Magic, and we've already established that FM is at least sorta sentient. Therefore, it wasn't just Frank, nor was it just the FM. It was both of them acting together to avenge themselves and the Family. It's not expounded on in the fic because Sirius already understands the nature of viewing FM as an independent entity.