"Son of Rap Bear" is the third episode in the ninth season of Adventure Time. It is the two hundred and sixty-ninth episode overall.
When Flame Princess is coaxed into a high stakes battle against the indomitable Son of Rap Bear, Finn must help her search for a new strategy.
Finn and Flame Princess socialize and rap together at a "Clam Rap" Party. Toronto (disguised with a fake mustache as "Victor Marilyn" and saying he's a talent scout) approached Flame Princess, impressed by her rapping, offered to book her for a big-time rap battle called Rap Fest-aide. He asked Phoebe to sign some waivers, which she did so with no hesitation. Toronto's fake mustache then fell off revealing his identity. Toronto then revealed the contract FP signed says that if she loses the rap battle, he will gain ownership of the Fire Kingdom and revealed that she'd be facing Son of Rap Bear.
Wondering who Son of Rap Bear is, Finn and Phoebe went to go visit Rap Bear. Finn noticed Rap Bear's poor condition, and Rap Bear revealed that he was beaten by his son in a rap battle. Upon telling Rap Bear bear the FP would be facing his son, he said he'd take her apart and revealed to not have legs because his son had "rapped his legs off."
Finn and FP went to the Candy Tavern to watch Son of Rap Bear perform. During the rap battle, Son of Rap Bear literally tore his opponent into pieces. Son of Rap Bear then spoke to Flame Princess rapping about how she'll never defeat him, and that she has no experience or anything to rap about, literally breaking the furniture and walls with his rapping.
Phoebe realized that Son of Rap Bear was right and that she needs life experience to rap about. FP then suggested that she and Finn go on adventures to have life experience to rap about. FP then rapped in montage throughout her adventures. Despite her new life experience, Phoebe still didn't believe she could defeat Son of Rap Bear. BMO then went on to comment on Neptr's "family," giving Phoebe an idea.
Flame Princess goes to visit her father in his new cave home among the chipmunks. FP proposed to her father about putting their past behind them and being "normal" with each other. Flame King then forgave his daughter for placing him in the lantern, though he didn't apologize for putting her in the lantern. FP then left in anger.
Rap Fest-aide then began with Toronto as an announcer introducing Flame Princess and Son of Rap Bear. Son of Rap Bear then begins to rap, particularly about Flame Princess and broke parts of the stadium in the process. Flame Princess proceeded to rap, though not very well, running out of rhymes quickly. FP then sees Flame King the audience, but he says he had no idea that she'd be there and that she in no way could defeat Son of Rap Bear. Enraged, Phoebe speaks in rhymes about how her father never cared for her and that she wondered why she believed the two could ever get along. FP then raps, ripping on Son of Rap Bear, impressing the audience, scaring Toronto and presumably defeating Son of Rap Bear. The crowd then runs up to Flame Princess cheering her on and declaring her the winner. Son of Rap Bear then raps to himself about how he lost and his legs fall off. Flame King then congratulates his daughter saying she's not bad.
- Jake (non-speaking)
- Rap Bear
- Marceline (cameo)
- Bun Bun (cameo)
- Kim Kil Whan (cameo)
- Starchy (cameo)
- Blank-Eyed Girl (cameo)
- Banana Man (cameo)
- Wyatt (cameo)
- Elder Plops (cameo)
- Flambo (cameo)
- Candy People
- The rapping chipmunk that performs for Flame King is voiced by Open Mike Eagle, who also happens to be the co-host for an Adventure Time podcast called Conversation Parade.
- Cinnamon Bun doesn't have his Flame Shield in the beginning of the episode, like in the episode "The Mountain."
- When Flame Princess sings "climb a rock," she appears to be actually climbing an insect husk, which is very similar to the shells of Ohmu from the manga and film Nausicaä of the Valley of the Wind.
- Rap Bear lives inside the monster from "Belly of the Beast."
- Flame King and Bun Bun still live in their chipmunk cave from "Bun Bun."
- Crab Princess makes an appearance for the first time since "Breezy."
- Dr. Dextrose makes a cameo appearance in this episode. He has not been seen since the season 2 episode "The Real You."
- A blank-eyed girl from the episode of the same name makes a cameo appearance.
- At the beginning of the montage with Flame Princess' rap, Finn appears with both arms.