I've been thinking about it, and I think I figured out FP's purpose. Obviously since she is staying on the show forever and there's practically no way they can write her in as a character if they break up, this is why she was implemented: She's just a new character to have fun with and cause cool adventures, in which maybe she partakes. If you saw ignition point, you saw that, at the beginning, Finn, FP, and Jake were just hanging out like buds and watching FP's cool powers. So here's what I think. Finn and FP will stay dating but there will be hardly any mushy gushy stuff anymore, after burning low. The writers would NOT do that. She's just like PB or any other female, fun character, but she's dating finn. This is the only way they could write her into the show. The designers came up with a character that everyone liked, they decided to give her a good personality, but the only way to write in a character that cute and that perfect for finn, would be to make them dating. SO, at first, they HAD to include the mushy gushy stuff, to show that finn and her would stay together cause they really liked each other, SO they couldn't really give her a developed and clear personality to start with, because she was so overloaded by all of finn's "liking her alot". They will include a little romance here and there so that finn and her can find a way to be together, only furthering the display that they will stay together. WCs, please find someway to leave comments without saying something like "that stupidity overloaded my brain" and stuff.