Lady Rainicorn is Princess Bubblegum's trusty steed and transports. She is also Jake's boyfriend and can speak Korean and sometimes follows them in their adventures. In the episode Lady and Peebles it was shown that she was pregant.
She is a long rainicorn creature with blonde long hair and has rainbow stripes in her body. Her mom has a long body like hers, unlike her father. This means that she inherited her length from her mother, since in the episode "Her Parents" her mother and father don't find it odd that Jake can stretch or is long like the females before they know he is a dog. Because Ethel's body is longer than Lady's, and Bob's body is much shorter.
It is shown in the episode My Two Favorite People Lady Rainicorn explains to Finn that she can fly because her body can intercept beams of reflected light from the sun and "dance around" on them. She could also play the viola like Jake whcih they do it every 4:00 pm. She can change the color of anything it is shown in the same episode, when Jake said to make that river green.
She can only speak Korean but can understand English. Lady Rainicorn, unlike both of her parents, doesn't wear a Universal Translator. It is worth noting however, that Lady Rainicorn understands English, but either cannot speak it or chooses not to. This is obvious because of the fact that neither Jake nor Princess Bubblegum speak Korean very often when talking to her.
Jake is her boyfriend and that they get along so well because of their common interest in the viola. This relationship began in the short when he and Lady Rainicorn were flirting and sharing interests. At the beginning of "Slumber Party Panic," she is shown being playfully chased by Jake, and later in the episode, they both seem to very much enjoy playing "Seven Minutes in Heaven" (which is a game where two people are locked in a closet together to kiss for 7 minutes). In "My Two Favorite People," Lady recalls a time when she and Jake ran naked through a farmer's field, causing Jake and herself to blush which may indicate some level of intimacy in their relationship. In "My Two Favorite People," Jake is torn between his desires to go adventuring with Finn and hanging out with his girlfriend. Lady later says she loves Jake "because he's an idiot" and that he makes her "feel like a genius." In "Video Makers," Jake gets very jealous when Mr. Cupcake flirts with Lady and becomes violently protective of her. The relationship appears to be rather serious, as he also was worried about his impression on her parents and even went to say he was studying Rainicorn history for their future children, which he did in "Paper Pete" to the point where he was so obsessed that he refused to help or acknowledge Finn's troubles, though he eventually gave up the information having gone way over his head. Lady's mother Ethel referred to Jake as hers and Bob's future son-in-law, hinting that she can see them getting married. In Go With Me, Jake takes her to the movie night and they ended up making out through the whole movie night. In the episode "Burning Low," Jake explains to Finn about "tiers" in relationships and is talking about his relationship with Lady Rainicorn in the process. Jake's implications in the explanation indicate that he is very intimate with Lady. In "Lady & Peebles," Rainicorn reveals in English that she's pregnant. In "Five More Short Graybles" she sports a baby bump on her belly when Jake put his thumb in it making her kiss him. In "Up A Tree" she is with Finn and Jake having a picnic. Later in the episode he takes her home as she kissed him.
In the beginning of episode "My Two Favorite People," Lady Rainicorn and Finn's relationship is awkward because of the language barrier. Attempting to fix this, she helps Finn and Jake recover the Universal Translator at the bottom of a lake guarded by Lake Knights. At first, Finn is worried that she is "too sweet" for the deadly adventure, but is quickly impressed by Lady Rainicorn's ability to fight. Finn also finds the translator's 'Old Man' voice option amusing, so he and Lady soon become friends. Jake gets rid of the Universal Translator, but any persistent issues Finn has with understanding Lady Rainicorn have yet to be mentioned.
Lady is usually seen with or near Princess Bubblegum in the Cotton Candy Forest in the Candy Kingdom. In the "Animated Short," she shows great concern when the princess is abducted by Ice King, and even tried to rescue her from him. She is sometimes described as the princess' pet. In "What Have You Done?," Lady flew the princess to the Ice Kingdom so she could ask for Ice King's help in ending the plague in the Candy Kingdom, and showed great disgust at him when he mistook their pleas for help for flirting. Lady even speaks to him at this time, saying "Verily, you are a creature unworthy even of my lady's disdain." When Lady got injured by the eyes in "Lady & Peebles," Princess Bubblegum showed great concern for her. This shows that they connect and have a deep friendship.
Lady's mother, who appears in "Her Parents." She is very shy to everyone but Jake, Bob, and Lady. She referred to Jake as her and Bob's future son-in-law.
is Lady's father. Bob appears in "Her Parents", and is very impressed with "Rainicorn" Jake.
- It could be possible that she might have a gender-swapped version.
- She has nightmares sometimes
- She could speak few English words like I am Pregnant
- In the episode Her Parents there are different kinds of traditonal games and about the Rainicorn and Dog Wars.
- In "My Two Favorite People" Jake refers to her as "the rowdy queen."
- In the episode Slumber Party Panic Jake and Lady did the 7 minutes in heaven.
- Lady's colors are the same colors of the rainbow
- In the Animated Short she had orange in her body but in the series they weren't.