I finally watched Fionna and Cake season 2 and, to no one's surprise, I have thoughts about Finntress:
I feel like their personalities complement each other very well. They're different in some ways, but for the most part they're very similar in their convictions and in their stubborn persistence. They're a force to be reckoned with.
It also makes a lot of sense for Finn--a very earthy and adventurous man--and Huntress--a protector of the forest whose wizardry revolves around plants--would gravitate toward each other.
I feel like Huntress is the only love interest that Finn has ever actually, truly respected as an equal. He doesn't idolize or obsess over her like he did with PB or FP, and he doesn't push her boundaries. They just have this mutual understanding and respect for one another that I really appreciate.
In extension, their on-and-off relationship makes a lot of sense in this context. Finn wears his heart on his sleeve, and I don't think he would have been satisfied with something so casual from anyone else. He's just happy to be around Huntress whenever she's there.
I love how Huntress' emotional vulnerability (or lack thereof) is represented through her mask. One moment that stands out to me is the scene where Finn says he's thinking of dying soon, and Huntress (sans mask) says "bummer! You're gonna forget all about me," while she lays relaxed against him. I don't think this is an exchange that would have happened in real life.
Also, Finn's "Never! Never." in response is just augh.
The way that Fionna assures Finn that Huntress loves him and the first person he sees when he wakes up is Huntress, smiling with tears in her eyes as she says his name, just makes me so happy.
Huntress definitely braided Finn's hair at the end of the last episode.
It's implied that Finn moved in with Huntress, which I of course love, but I also weirdly love that Neptr is there, as well. That's their son now lol.
It's crazy to think that Huntress was just a background character for most of the series.