What If Snape went to the Potters? Feb 1980
Serverus Snape is at Death Eater HQ trying to ignore the idiots around him when Peter Pettigrew arrives all excited and reports to Lord Voldemort some exciting news – he's just overheard a Prophesy being made in the Hog's Head pub by Sybill Trelawney's talking to Albus Dumbledore; Voldermort is about to dismiss Pettigrew with a Curio, but the rat explains that Trelawney's voice went all strange just before she spoke:
"The one with the power to vanquish the Dark Lord approaches... born to those who have thrice defied him, born as the seventh month dies... and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not... and either must die at the hand of the other for neither can live while the other survives... the one with the power to vanquish the Dark Lord will be born as the seventh month dies.…"
Voldermort is quite alarmed by this and asks his assembled Death Eaters for the names of well-known pregnant Witches who have defied him, who might are likely to give birth in July. Pettigrew immediately says Lily Potter, which raises Snape's hackles- up to now the presence of Pettigrew has been an amusement at how one of the 'perfect' Marauders could betray them, but mentioning Lily being in danger, and all the old feelings and memories rush back. Snape immediately mentions Alice Longbottom as a possible option, pleasing Voldermort, who then dismisses the Death Eaters so he can think about this news.
As they leave Snape is thinking hard, he needs to get a warning to Lily. Her oaf of a husband he does not care about, but if he just turns up on their doorstep, he is likely to get arrested, he needs a way in, and Regulus Black comes to mind. Black was mysteriously badly ill at the end of '79, and Voldermort had sent him over with unregulated potions to help him recover (Riddle cannot lose the Black money), while there Snape brushed Black's mind and learned of the amulet Horcrux, and Black's own wish to leave the Death Eaters; which when Snape thought about it long enough, so did he- outside of Hogwarts the insanity of Riddle didn't buy much, and the methods the monster used? Uncivilized and barbaric. Black had got better thanks to the potions, and the pair of them had hatched several plans to escape the madman, but nothing had come to fruition yet.
Snape meets Black post meeting, for their usual 'port and chat' at 12 Grimmauld Place, and Snape outlines a plan to Regulus, who agrees its risky, but will go with it. Kreacher is sent to find, and transport Sirius to them. When Sirius is brought to them, he is bound with ropes and gagged- Kreacher had obviously enjoyed his task. Snape and Black stood in a bare, empty room with their wands on a table in front of Sirius. Snape tells him they have information that will win the War, but he needs to hear them out first. Sirius agrees, - if they wanted him dead, he'd be dead after all. They provide him a chair and unbind him, then Serverus and Regulus tell Sirius the story of the horcruxes and Pettigrew bringing the prophecy. They offer to provide memories, and of course, he can verify with Dumbledore. Sirius will do so, and takes the memories offered. Krecher, then (more reluctantly) returns him to whence he came.
Three months pass with no news. Snape and Black play the proper Death Eater members, though Snape recruits Black as his potions assistant to stop him having to go out on raids. Riddle remains in the dark due to mind shields. Pettigrew come to one meeting in obviously under an Imperious, or possession; when he asks if his Lord has thought on the Prophesy more, Voldermort replies he has and the Longbottom's are the most likely candidates as both of them are pure-blood Aurors who had defied him, making them more likely candidates than blood-traitor Potter. Voldermort is going to wait to see when their child is born before striking though.
In late May Snape receives a letter from Lily inviting him to a meeting in Cokeworth- at the playground they used to meet at. Snape obviously goes, with Regulus as backup. Serverus and Lily meet- she is heavily pregnant. They both know there are others watching from the shadows. Lily asks how serious he is about leaving the Death Eaters and Serverus is very adamant at wanting out. Voldemort is only getting worse, and even if he is getting stronger, the Death Eater campaign of terror is not what he and Regulus signed up for. Lily says she has been researching the tattoos the Death Eaters use and is on the track to be able to remove them but needs more information. Also, they need more clues about the horcruxes. Lily tells him the Order has been able to find one- found in the Gaunt's shack when digging into Riddle's background, but without more info they are stuck. Serverus agrees to see what he can dig up. Pettigrew is now being watched, and tracked she confides. Snape asks her if she has considered using magic to delay the birth and thus disqualifying the child from the Prophesy? Lily is surprised by the suggestion- Dumbledore had not even offered it as an idea- Snape scoffs and begins to tell her Dumbledore is not a good man, but changes his mind before he gets out but a few words- he does not want to drive Lily away, instead warning her to check Dumbledore's background and she will find he is not as white as he seems. They agree to meet again in a month- or after the birth.
During June and July, Snape and Regulus dig about for more information- they discover Voldermort has given Malfoy objects of power, and Bellatrix all but brags of her Lord's trust in her, but what the objects are they cannot find out. Though they discover from stolen/copied Journals that Riddle found the Chamber of Secrets and the Room of Requirement at Hogwarts, as well as travelled extensively in his post Hogwarts youth looking for objects of great worth. The information is past on at another meeting in mid-June on a beach in Wales. At this one Lily tells Snape that Dumbledore is not taking the threat seriously, and she had to find out about birth magics independently. She has also checked into Dumbledore's background, and been disturbed by some things she found, but for now they need him.
July 1980 passes slowly for Serverus- at the end of the month the birth of Neville Longbottom is announced- which Voldermort seizes on at proof he was right about the Prophesy's as the 'mudblood could not even give birth on time'. Lily gives birth on August 8, but by then Voldermort is not in a good mood as the Longbottom's have gone into hiding under the Fidelius Charm and the Dark Lord is not pleased and all Death Eaters feel his wraith, and are sent out to find them.
In August Orion Black dies and leaves everything to Regulus, who then uses his access at Head of the Black Family to get an inventory of all Black vaults. In Bellatrix's list a recent deposit of an 'ancient cup' spikes his interest and he uses his family Head powers and a very hefty fee, to get her vault opened without her knowledge and removes the obviously evil cup- leaving a copy. Research soon reveal it to be Helga Hufflepuff's Cup, which given Riddle had used Slytherin's Locket in the cave, suggests he was using items the Hogwarts Founders used, though the exact number he made they still don't know.
October brings an attack on Pettigrew in the street that sees him arrested by Moody and exposed as a Death Eater. The shock of a Gryffindor Death Eater reverberates around the community, with Moody swearing at a Prophet reporter- "well did you really think they all fucking came from Slytherin?" Pettigrew of course sings like a canary under interrogation by Bartemius Crouch, and Moody, and raids are arranged across the whole of country on Halloween, with a major one on Malfoy Manor where Auror's Black and Potter have a secondary agenda from just nabbing the family. The raids are successful in collecting large numbers of Death Eaters, and many claim they were under Imperious; however Crouch will have none of it and all are tested under Veritaserum, and many high ranking pure-bloods are outed from all Hogwarts Houses, and even from abroad. The ICW finally start to take notice of the situation. However, the raids have created trouble around Crouch when his son is arrested and outed as a Death Eater, which then wraps the Head of the Department of Magical Law Enforcement in a scandal. Crouch disowns his son to save his job.
Voldemort is incensed about the raids and targets prominent Aurors – managing to kill Edgar Bones, Thesus Scamander, Gawain Robards, Benjy Fenwick, Caradoc Dearborn, and seriously wound Moody. With the Death Eaters exposed, Voldermort steps up his campaign overall; Minister Bagnold is targeted but survives; former Minister Minchum is murdered. Attacks on Muggle-borns increase, and the Hogwarts Express is bombed, though only the engine is destroyed, it causes chaos at the start of the Hogwarts year. A raid on Azkaban during the prisoner transfer kills Pettigrew- but few escape as Dumbledore appears to duel Voldermort- injuring him, and forcing a withdrawal under extreme firepower, however Voldermort is re-joined by the Lestrange brothers and Malfoy.
While Voldermort is leading the assault on Azkaban, Snape and Black raid the Riddle Manor, with help from Sirius, Lupin, Potter, and the Prewett brothers. They rip open all the hiding places, (Snape and Black use wands taken from Aurors) and remove anything that looks personal to Voldermort or his followers. As a parting gift they burn the Manor to its foundations. A fake body is left for Regulus, as it is agreed it is time to extract him. Snape re-joins the Azkaban raid in time to join the retreat. Voldermort has not missed them, though Bellatrix is suspicious. Voldermort's delight at the return of some of his prominent Death Eaters is tempered by the burning of his headquarters, and they instead take over the now vacant Crabbe family manor.
The raids and counterraids continue through the turn of the year. Snape is only able to get away at the end of February, as Voldermort has him brewing non-stop. Riddle has him mass producing hysteria potions, fear potions, and magical bombs. Serverus only gets away when Voldermort himself goes on a Hogsmeade raid. Snape is able to meet Lily only briefly, and she tells him she was able to remove the Mark from Regulus. They discovered a horcrux Diary at Malfoy Manor, and Ravenclaw's Diadem at Hogwarts, but need to know if that was all of them before a confrontation can take place, only then can Riddle be killed for good. Snape suggests checking back with Hogwarts staff, and anyone Riddle knew well to see if they know anything, then they part.
During the Summer Voldermort gets his hands on some major Ministry records, and takes his campaign to the Muggle world- attacking Mudbloods and blood traitors at home; Andromeda Tonks is killed defending her family, but drives off Bellatrix. The Figg's, Cresswell's, and Boot's are all killed. The campaign threatens the International Statute of Wizarding Secrecy, but Voldermort dares the ICW to 'do anything' to stop him in an exclusive in the Quibbler- the mad editor risking death to get an interview- the ICW do nothing. Death Eater agents are sent to the giants, werewolves, and other such 'monsters' to ready for 'a significant October attack'.
September 1981 – The country is in the grips of full on terror. Voldermort has put a trace on his name- appearing or sending agents to kill anyone who speaks it. Dumbledore resists this and duels Riddle repeatedly; always to stalemates, or Voldermort leaves. The Death Eaters have replenished their numbers to a certain extent, partly 'volunteers', partly 'monsters'- Greyback has been unleashed to create as many Werewolves as possible- even managing a full moon attack on Hogwarts himself wherein he infected six children and the Potion Professor Slughorn out gathering potion supplies.
Snape has gotten nowhere finding out any more about horcruxes, or gaining any more free time. Even when Voldermort is away, he has to brew. He suspects Riddle is keeping him busy during the period of raids as he suspects something. As it turns out it is Bellatrix who has been arranging the timing, she has been suspicious of him for a while, though she can prove nothing, they clash angrily.
October 25th: Voldermort gathers his commanders- he has obtained the address of the Longbottoms via a traitor in the Order- Remus Lupin, who bent under pressure/torture from Greyback and other werewolves. They will raid on Halloween in force. Snape is bent double brewing in time for the raid- he makes the potions slightly flawed; they will run out a little early, or not be at full strength etc. Given how much he is making no one questions him.
The raid on Godric's Hollow was massive- all the remaining Death Eaters, several Werewolf packs, and set of Vampires. It was too far south for the giants, but the Hags made it. They descended on the village with Voldermort at the head of the group. Anti-portkey, and anti-apparition wards where set up. Voldermort let loose his Monsters to kill all in the village, while he charged into the location of the Longbottom's cottage, ripping the Wards apart, exposing the house, before storming in himself.
Inside the cottage was Dumbledore – Voldermort readied himself for a duel as Dumbledore calmly explained they knew about his horcruxes, how many he made (thanks to Slughorn), and that they were being destroyed right NOW – Riddle felt the destruction immediately, the pain drove him to his knees as his soul reacted. Dumbledore then bid him goodbye and fell over- he had never been there just a very detailed homunculus messenger which exposed the face of a bomb as it fell- a very powerful, but mundane bomb- which went off at exactly 8.12pm killing Tom Riddle instantly.
The Death Eaters, and Monsters that roared across Godric's Hollow found themselves facing The Order, Aurors, and mundane SAS snipers firing hidden from the trees. Bellatrix went down fighting James Potter, who managed to decapitate her with a cutting curse at the cost of nearly losing his left arm. Greyback went down to a vengeful Remus Lupin who ripped out his throat with his claws, having long ago balanced his Wolf spirit and learned how to part-shift. Lucius Malfoy was killed by a Muggle sniper while fighting Sirius. Arthur Weasly lost an eye during the battle, Moody nearly died from poison, but careful planning and luck potions prevented many more deaths.
At 7.55pm Snape was kidnapped from the battlefield by Kreacher who transported him to a field in the Forbidden Forest wherein Lily used a short ritual she had invented to remove his Dark Mark. Snape then witnessed the destruction of the horcruxes by Dumbledore, Regulus, and Filius Flitwick using Fiendfyre.
When Voldermort died, there was massive physic feedback to the remaining Death Eaters which paralysed them and allowed their enemies to incapacitate them. The Mark itself left a massive skull shaped burn on the arm, impossible to hide or fake. The remaining attackers are rounded up.
In the investigations post Battle of Godric's Hollow Minister Bagholt wanted to publicly reward Serverus Snape and Regulus Black, but both refused any public ceremony, though both were awarded the Order of Merlin, First Class privately instead. Their role was obfuscated in the official records. Albus Dumbledore was also somewhat marginalised as Minister Bagholt was informed of several irregularities in his records and family history by Lily Potter.
Serverus went into Potions Making full time, and became 'Uncle Sev' to Harry Potter, having buried the hatchet with the Marauders. Regulus Black added the Tonks, and Sirius back to the family tree, though Sirius refused the head of Family title leaving that with someone who took it seriously.
Tom Riddle remained dead forever.