Finn while over-zealously re-committing himself to his job as Bubblegum's champion, annoys her and is sent to go hang out in a junk yard where he meets an old gumball robot swordmaster, who he convinces to train him in the art of sword fighting.
Tropes
- Call-Back: Finn's intensity in resuming his hero duties is an attempt to get over his breakup with Flame Princess. Or at the very least an attempt to distract himself and quit annoying Jake.
- The Champion: Finn attempts to refresh this role for PB.
- Continuity Nod:
- Finn still has his Grass Sword attached to his arm.
- Finn still has an immunity to heat due to being with Flame Princess.
- Root Beer Guy is still Da Chief.
- Defector from Decadence: Rattleballs when he realized Bubblegum was going to destroy them.
- Eyes Always Closed: Rattleballs has this look as a default expression.
- Gilligan Cut: From Rattleballs making Finn swear to keep his existence a secret to Finn blabbing the whole thing to PB.
- Girly Scream: Twice, first when PB finds Finn in her kitchen first thing in the morning, and second when Finn thinks Rattleballs is about to blind him.
- Gone Horribly Right: Rattleballs was part of a robot force Bubblegum had programed to protect the Candy Kingdom. But since they were programed to fight they spent most of their free time doing so in ring matches. Bubblegum deemed them too dangerous and had them destroyed save for Rattleballs who had gained sentience and managed to avoid execution.
- It's a Long Story: Subverted with Rattleballs' Dark and Troubled Past. He describes it as a long and harrowing tale when Finn asks about it... then immediately begins the story.
- Last of His Kind: Bubblegum crushed the rest and attempted to recall Rattleballs as well.
- Lightning Bruiser:
- Rattleballs using the Shadowless Thrust moves very fast without wind resistance.
- Finn is also trying to learn this technique.
- Martial Pacifist: Rattleballs
- Master Swordsman: Rattleballs himself. He can do a "Shadowless Thrust'' which can cut objects around a person without hitting them and in the fight against the Banana Guards he manages to take them all down without fatally harming anyone.
- Old Master: Rattleballs, who's older than Candy Kingdom itself.
- "Second Law" My Ass!: Rattleballs had to use all of his willpower to turn away from the wall, look at the massacre of his fellow machines, and escape. This is a rare instance when the trope is given to a good-aligned robot who isn't an anti heroic jerkass.
- Sliding Scale of Robot Intelligence: Rattleballs is probably a Grade 3, but he makes up for it as a Badass Normal.
- Technical Pacifist: When Bubblegum thinks he's slain her entire ambush squad, the squad is revealed to be bruised but alive, thus demonstrating both his skill and his self-control.
- Three Laws-Compliant: Rattleballs interprets the First Law loosely (see Technical Pacifist, above), plays the Third Law straight while the rest of his kind walk straight to the crusher, but…
- Undying Loyalty: Explored in this episode with both Finn and Rattleballs to Bubblegum. It ultimately pays off for the latter.
- Whole-Plot Reference: The plot of the episode is a virtually exact copy of the 1970s Superman story "The Secret Guardian of Smallville", but with Superman's role split between Finn and PB, and a happier ending. (In the Superman story, Superman tricks the sole surviving robot Superboy into believing that it has killed a human, causing it to self-destruct.)
- Your Eyes Can Deceive You: Rattleballs makes Finn run a gauntlet of traps blindfolded as part of his training.
