As soon as I typed it out I started thinking about it more.
So Finn is playing video games with TV, it's Compy's Castle and they're playing co-op and he's telling him they have to lower the draw bridges or Compy's bloodlust meter will go down. TV's asking him how he got good at this game and Finn tells him Jake is third best in the Candy Kingdom at it.
Finn checks the time "Oh snap, I'm gonna be late, catch you later TV!"
"OK, bye." and TV just starts using both controllers to play.
Finn's on the grassy fields and he spots a monster, a big monster with two heads chasing someone, it's Jake Jr. Finn upper cuts the monster right in the crotch yelling "YOU STAY AWAY FROM MY NIECE!" and as the monster lays crumped on the ground clutching his evil crotch Finn spits on him "Yeah, you better satay down."
"That was cool, uncle Finn!"
"No prob, I school boys like these all the time, let me know if anyone else give you any trouble."
As Finn leaves JJ goes through the monster's pockets and steals his wallet, the implication being she was being chased in the first place because she donked up a pick-pocketing.
Finn arrives at a theater where he sits down with the band and begins playing the flute for Viola's recital or play or whatever, HW can be seen spying through a window since she's into Finn's flute playing skills. Afterwards Finn gives Viola a bouquet or something for her performance and she thanks him for playing for her.
As Finn's leaving Charlie catches him, she was in the audience, and asks him about the magic lady who showed up for his flute playing. "Oh, that's HW, we're kind of dating."
"Should I expect some cousins soon?"
"Oh yeah, I'll introduce you to him!"
"BAM! Meet your cousin Stormo! He's locked in an endless psychic duel with his half-sister to keep her from taking over all of Ooo. Stormo, this is your cousin Charlie."
"... hi Stormo."