Finntress

Finntress is the het ship between Finn Mertens and Huntress Wizard from the Adventure Time fandom.

Season 7
Huntress Wizard first met Finn in "Flute Spell," where she had came across him playing his flute while nude in a river. At the end of the episode, Finn revealed that he had been playing his flute for her, and in turn she revealed that she had been playing her flute for him. The two kissed each other, but she pulled away, stating that "exceptional beasts" such as themselves are not meant to be together. Later, in an episode titled "Wheels," when Finn played his flute in a skate park, she looked at him from behind a bush, which might indicate she still holds an interest in Finn and/or his flute playing.

Season 9
However, in the episode "The Wild Hunt," Huntress Wizard helps Finn by putting herself in danger to help him overcome his mental blockade. After that, Huntress Wizard flirts with Finn by saying "We both know you're totally in love with me." She then accepts another kiss from Finn. In "Seventeen," Huntress Wizard attends Finn's birthday party and gives him an elk's heart in a box as a present, which could possibly be read as a token of affection. She helps fend off an attack by Fern and Gumbald, and offers Finn help by telling him to eat the heart to gain strength, though this only winds up making him sick.

Fanon
At the beginning many fans did not have the idea that Finn would have a third girlfriend after having broken with Flame Princess, some had the intention of matching with Huntress Wizard for being a relevant character, in the end it became a reality in the episode " Flute Spell".