Fern

 (full title: Fern the Human, formerly known as Grass Finn, or the grass guy) is the result of Finn's Grass Sword and Finn Sword merging into one being. He makes his first appearance at the end of "Reboot".

Appearance
Fern's original form looked like a humanoid figure made of grass.

He later took on the appearance of Finn the Human. The notable differences compared to Finn however, is that he's entirely made of grass, from his skin to his hair and clothing; have blockier proportions, and is barefooted with two toes on each foot.

Personality
He originally talked in gibberish-like words, an example being "Mwah!", but he soon learned how to speak and hear normally.

As he was recently created, he doesn't understand much of what is considered right or wrong, and originally thought of himself as the true Finn, before he took on his own personality as Fern. He is friendly towards Jake and Finn and has a happy-go-lucky attitude, though he is slightly aggressive.

Abilities
Being entirely made of grass, he has the ability to change his appearance and shapeshift into any form he can think of in order to fight enemies. In "Do No Harm", he alters his hand into a grass sword to slice grass monsters in half with a single swift stroke. He also changed them to huge thorny fist-like projections to beat up the Grassy Wizard. The main downside to these abilities is that being a body of grass, he can't eat like a human despite being able to taste, smell, and remember food.

Major appearances

 * "Two Swords" (not named yet)
 * "Do No Harm"

Minor appearances

 * "Reboot" (debut, not named yet)