This is right after 'Sky Witch' ends.

Princess was holding Marceline, not to fall. Marceline planned to bring her to the cave, just to say thanks and be polite. Least thing she could do. She didn't want to, but she retrieved the most important material thing to her.
"Marceline, what are we doing in your house?"
"Oh I just wanted you to chill for a while. You know, everyone in your castle are bonkers and or asleep." Marceline said grabbing 2 apples.
"Well, thanks, but why is that so important to you?" PB said while sitting on the floor and pointing to Hambo. Marceline threw her an apple and she sucked the red off of hers.
"Lets just say, its what i kept from the war." She said sighing and sitting beside PB.
"Oh my glob. Sorry." She said putting her head on Marceline's shoulder.
"Its fine. Not your fault. It was m-my" Marceline starts to tear up.
"It was a guy named Ash. Am I correct?" PB said sitting upright.
Marceline wiped her tears and spoke to PB in a choppy voice.
"H-how di-did yo-"
"Maja had a receipt of purchase. Thats how I *sigh* got Hambo back." She put her knees to her chest and hugged them.
"Tell me how you got Hambo. Please." Marceline wasn't sad anymore. She was more confused.
"I made a trade." She said avoiding eye contact
"With what?" She said staring at her
"Y-your shirt." She said sniffing her coat, lightly.
Marceline was confused. Ash traded Hambo for what was it?

"Yuh, thats why I traded it, it had a shitload of sentimental junk, genius."

"Sentimental value." Marceline whispered to herself.
"I was wearing it today, under my coat. If you remember, today is the anniversary we met each other." She said clasping her hands tighter.
"Im sorry. Today was also the anniversary of my breakup with my abusive bf." Marceline put her arm around PB.
"Abusive? H-he hurt you?" PB asked giving eye contact to Marceline. She couldn't care less if Marcy saw her crying.
"Verbally. He was close to hitting me before but I attacked first. He told me to make a sandwich right after telling me about selling Hambo, as if it were nothing."
"Not to sound rude, like a while ago, what happened with Hambo? Like backstory."
"My father-figure gave it to me before an i-infection got to him. He was infected ever since an attack, but he calmed himself down by this chant from some TV show. I would sing it to you, but now isn't a good time for my voice, if you can't tell" Marceline said trying to smile.
"don't worry. you didn't know a while ago." Marceline said wiping her tears and she stood up to go to her room. Before PB could say anything Marceline's hand motioned her to follow. She stood up and walked there. Her legs were quite weak from crying. She was by the stairs and she saw Marceline in her closet.
"Bonnie, come here for a sec." Marceline said after seeing her by the stairs. She walked towards her and waited behind her.
"Here. Its my favorite shirt. This was what I wore when we went to the concert together, remember?" She gave her a wrinkled black and red shirt, similar to what she already gave her. It had the band's logo on it and everything. PB took it and sniffed it. Her shoulders suddenly relaxed. She then hugged Marceline.
"Thank you. You are my best friend. It doesn't show, but you are." She said while Marcy was caught off guard.
"No, thank you." Marceline whispered
PB then slowly pulls away and leans in to her. Marceline didn't know what to do. She stood there motionless. She has always loved her, even before Ash. Why couldn't she respond. PB kissed her and she was just stood still.
"Marcy I-" She said slowly after bing cut off by Marcy hugging her tightly.
"Bonnie, please." Marceline said kissing her again. PB returned the kiss.
"I love you." PB murmured after the kiss. Their foreheads were touching and the atmosphere changed almost automatically. From a sad, thick air-ed room, to a lighter and warmer mood.
"I always have, Bonnie."
"Ash was a douche. He didn't deserve you at all." She said smiling.
"I sure hope I deserve you." She said stepping away from her. She grabbed her Axe Bass and sat on the bed. PB sat in front of her.
"I sorta promised a song, didn't I?" She said smiling. PB then went beside her.
"This is what happened when me and my 'father' saw each other again."
She strummed her bass and sang.
"Is it just you and me in the wreckage of the world. It must be so confusing for a little girl. I know you're gonna need me here with you. But Im losing myself and Im afraid your gonna lose me too. This magic keeps me alive, but its making me crazy. I need to save you but who's gonna save me? Please forgive me for whatever I do, when I don't remember you. La da, la la la la, lada, ladadada la la, la." She put and arm around PB.
"That was amazing." PB said resting her head on Marceline's shoulder. Marceline ribbed her arm and felt her goosebumps.
"Wanna wear the shirt under? I think you're cold"
"Sure, do you have a comfort room?"
"Yeah, its just there." She pointed.
"I will be right back." She walked there and slightly closed the door.
Marceline couldn't help it. She turned invisible and sneaked a peek of PB. How could she not? She then saw her sniff it first before wearing it. She blushed and thought to herself to just turn away. Not the most badass thing to do, but Marcy seemed to love her more than just for her appearance. She sat on the bed looking through sheet notes she always has on her bed. She giggled when she saw one song. Right on time, PB went out of the room.
"I feel much better now, Marcy!" She said smiling and hugging her torso.
"Glad you like it, Bon. Great timing sit here." She said patting the seat. She walked beside her. She then snuggled beside her, knees to her chest and smiling.
"Remember this, Bonnie?" Marceline said playing a reminiscent tune.
'La da da dada, I wanna bury you on the ground.
La da da dada, Im gonna bury you in my sound.
Im gonna drink the red, from your pretty pink face, Im gonna-" she sang smirking
"Marceline, thats so distasteful!" PB said giggling
"Oh you don't like that? Or do you just not like me?" She said in a teasing tone, while playing a random string on her bass.
"Oh glob, such great memories!" PB said playfully pushing Marceline
"So much changed didn't it?" Marceline stated
"Glob yes. I remember Finn still had a crush on me! I was also worried that you would know my secret crush on you that day!" PB said like a teenage girl
"Not a secret anymore." Marcy said kissing her cheek. PB couldn't help but blush. She was even pinker than usual, and thats an achievement.
"Bon, are you okay?" Marcy said looking worried
"I am very okay! But the kiss..." She said putting her fingers on the place Marceline kissed it, trying to remember the feeling.
"Sorry, I thought we were like a couple and stuff..." Marceline said rubbing the back of her neck.
"N-no, don't take it the wrong way I liked it a lot!" She said waving her arms and hugged Marceline as an apology.
"Y-You did?" She said as her eyes shot open. PB pulled away. Their faces were practically centimeters away from each other.
"Of course! How could I-" pB said as she was cut off by a kiss on the lips. It was gentle and emotional. That surprised the princess, her shoulders tensed and her eyes closed shut. After a second or so, she loosened up and returned it. As they pulled away, they both had a tint of rose on their cheeks.
"We should do that more often." Marceline said smirking
"Totally." PB said before giving another affectionate kiss.