⭐ so u may have noticed that in one of the new doodles, fennel doesnt have rabbit ears but fionna does. well, thats post-golb fennel. non magic. and thats post-prismo fionna. and u may be thinking well why does fionna even have ears shes nonmagic to begin with. ok so headcanon time. founders island did a lot of genetic modification and gene splicing. not just with seekers but sometimes helpers too. so yeah fionna has a bit of rabbit genes because of gene spliced ancestry.

⭐ to sorta tell which part of the timeline it is, ill put it like this. pre-golb fionna has the rabbit ears. post-golb/pre-prismo fionna does not have any rabbit genes at all. post-prismo fionna looks almost the exact same as pre-golb fionna. pre-golb fennel has the ears, claws, digitigrade legs, etc. post-golb fennel has none of that except the sharp teeth.

⭐ the reasoning as to why the helpers were gene spliced with rabbits is to improve efficiency, agility, and speed. and for finn, the helpers were gene spliced with polar bears to increase resilience, though strength was a nice side effect.

⭐ silly little thing. fionnas a rabbit. fennels a jackalope. finns a polar bear. and ferns an owlbear.

⭐ i love biology. especially genesplicing. but genetics in general is very fascinating.