i only hope you dont include treetrunks and lumpy-space-princess. That would be disgusting even by adventure time standards. Just leave finn with princess doctor until flame princess arrives.

FP, definitely...Although its gonna be interesting to see how you handle the interaction between them, I mean, its hard enough for finn to survive being closeby her at full size, but now that hes tiny its gonna be damn near impossible!

Good, story by the way, a bit of criticism though is to try to combine senteces more often, you had too many sentences that described one action and then quickly started another sentence to talk about something that could have easily been in the same sentence. An example is this part:

"She then pulls Finn out of her pocket. She thinks the insect is really weird looking so she brings its up close to her eye. She gasps realizing its not an insect but it is actually Finn the human. She then smiles and places Finn in her cleavage. She sees Finn trying to climb out but she quickly pushes him down with her finger. Marceline squeezes her breasts crushing Finn. She then starts flying back to her house."

^You could have combined some of those senteces and gave the paragraph a nicer flow and also reduced the word count, but overall good job...just wanting to help you get better at this.

I love this. please make her mean and playfull!