Finn makes amends at the Candy Hospital while Jake tries to connect with their unexpected houseguest.
Tropes:
- Bare-Handed Blade Block: Finn's plan to snap Susan from her coma is to drop a sword on top of her, thinking that her warrior instincts will kick in and she'll catch the sword in time. Fortunately, Doctor Princess intercepts it just in time. The Stinger shows that this probably would have worked.
- Bavarian Fire Drill: Doctor Princess' entire medical career is an unintentional one. She went into the hospital one day and everyone thought she was a doctor because her first name is "Doctor".
- Brick Joke: Finn's theory about Susan's instincts are proven correct at the end, when she awakes just in time to catch a falling blade from a ceiling fan.
- Clone Angst: Fern spends the episode coming to terms with the fact he's not actually Finn.
- Disappointed by the Motive: Turns out the Grass Wizard created the Grass Blade mostly for the sake of the pun, with no larger purpose. Grass Finn does not take it well.
- Failed a Spot Check: Mr. Fox had no idea its paw was hurting because there was a thorn stuck in it. Either he never bothered to look, or didn't think the thorn and the pain were related.
- Florence Nightingale Effect: Ice King clearly came to the hospital just to flirt with Doctor Princess.
- Hero Stole My Bike: Grass Finn/Fern takes Starchie's motorcycle and rides off to find himself.Starchie: No! Starchie's mid-life crisis!
- His Name Really Is "Barkeep": It has already been established that Doctor Princess is not a princess and "Princess" is her last name; now it happens that "Doctor" is her first name and she doesn't even have a medical degree.
- Hollywood Healing: Deconstructed; Finn's attempts at healing, which appear successful at first, fail because he didn't follow proper procedure. Mr. Fox's paw got infected because he didn't treat the wound after pulling out the thorn, and Ice King's back simply snaps backward after Finn's hasty adjustment.
- Identity Breakdown: Grass Finn starts to think that he's not Finn after all, but a completely different individual. In the end he decides to call himself Fern and goes off to find his purpose.
- It's All My Fault: Finn blames himself for what happened to Susan, as well as not being able to stop her when she went berserk.
- Riddle Me This: At the gate to the Grass Wizard's lair, a grass beast asks Grass Finn and Jake a riddle before he can let them pass. Grass Finn simply slashes him to bits before he even finishes the riddle, then says that the answer was probably time.
- Shoot Your Mate: When the Grass Wizard recognizes Grass Finn as one of his creations, he orders him to kill Jake for trespassing. Instead, Grass Finn simply beats the Wizard into submission.
- Shout-Out: Mr. Fox's "Ooh, it's the big one!" when he's talking about his injured paw could be a reference to Red Foxx's catchphrase in Sanford and Son.
- What the Hell, Hero?: Doctor Princess gives one to Finn after she hears him admit that Susan's injuries are his fault.
- You Make It Go On Break, You Bought It: Susan is in such critical condition that Doctor Princess becomes fed up with caring for her and makes Finn the new doctor upon hearing he's responsible for Susan's injuries.
