Lady Rainicorn

Rainicorn or Lady Rainicorn, is a unicorn crossed with a rainbow. She is basically Princess Bubblegum's pet, but more importantly her companion and is concerned with her safety. She does not speak English (except when equipped with a translator) and her main language is Korean, although she sometimes speaks other languages. She sometimes follows Finn and Jake on their adventures.

In the episode "My Two Favorite People" Lady Rainicorn explained to Finn that she can fly because her body can intercept beams of reflected light from the sun and "dance around" on them. In the same episode, she is shown to live in a cabin in the Cotton Candy Forest. She likes oranges and can eat half of an orange in a single bite.

Appearance
Lady Rainicorn is a long unicorn-like creature, with rainbow colored stripes along her body. She has big eyes, similar to Jake's eyes. She also has a horn and a blonde mane and tail. She has the ability to use her horn to change the color of anything she wants, as witnessed in My Two Favorite People. She may also have a fondness for Power Rings.

Personality
Lady Raincorn is laid-back and likes to interact with Jake and Princess Bubblegum. She's rarely sad or angry. In the Animated Short, she was seen crying. She doesn't speak Korean in the Animated Short; she only makes soft cooing sounds (or, near the beginning, hysterical screaming coos). However, Jake seems to understand what she says when he talks to her. She believes she is smarter than Jake.

Jake
On the official website in Rainicorn's description it says she is Jake's girlfriend and that they get along so well because of their common interest in the viola. At the beginning of Slumber Party Panic, she is shown being playfully chased by Jake, and later in the episode she doesn't mind being locked in a closet for 7 minutes with him. In My Two Favorite People Jake admits that he wants to stay and fight with Finn, but he also wants to hang out with his girlfriend.

Princess Bubblegum
She is usually seen with Princess Bubblegum and lives with her in the Candy Kingdom. She is sometimes described as the princess' pet. The interaction between her and Princess Bubblegum have not been explored in depth yet in the series.

Finn
In the beginning of episode "My Two Favorite People", Rainicorn and Finn's relationship is awkward, but gets better when she accompanies Finn and Jake find the Translator in the bottom of a lake. When Rainicorn puts on the Translator, Finn can understand her, and Finn is impressed by her ability to fight. They become friends, but Jake gets jealous of them hanging out. Finn and Rainicorn respond by telling him that they are just friends.

Quotes
Finn was able to understand Lady Rainicorn with the Translator in the episode My Two Favorite People.

See Lady Rainicorn/Quotes

Trivia

 * Lady Rainicorn is voiced by Dee Bradley Baker in the Animated Short, and she is voiced by Niki Yang in the television series.
 * In one room of the royal castle, there are two pictures of Lady Rainicorn on the wall: One of her upper half, and one of her lower half.