It's Adrien's birthday. Unfortunately, Mr. Agreste has no intention of allowing him a birthday party. Adrien's friend Nino tries to change Mr. Agreste's mind, but his efforts are fruitless. Armed with his magic bubble-wand, Nino becomes the Bubbler and plans to rid Paris of all the parents who prevent children from having fun.
- As You Know: A less obvious example than most, as the exchange is brief and doesn't call attention to the exposition.Tikki: You know what happens when you use Lucky Charm. You only have minutes before...
Marinette: ...I turn back, I know.
- Attack Reflector: Bubbler manages to send Ladybug's yoyo right back at her.
- Birthday Episode: Adrien's, to be exact.
- A Birthday, Not a Break: Not helped by the fact that your best friend turned into a supervillain, and that only one person remembered to get you a present.
- Comes Great Responsibility: Ladybug wastes her first transformation by using her Lucky Charm to get Chloé away from Adrien, instead of stopping the Bubbler. She has to feed Tikki to recharge, and Tikki calls her out for being irresponsible.
- Floating in a Bubble: The fate of Bubbler's victims. Including Cat Noir and Ladybug, after they think having successfully deflected all his bubbles.
- Getting Crap Past the Radar: When the Bubbler traps Ladybug and Cat Noir in a bubble, Ladybug points out they have to escape and can't be trapped forever. Cat Noir gives a knowing grin in response.
- Happiness Is Mandatory: If the kids don't have enough fun, Bubbler traps them in bubbles, just like adults. For not being free enough.
- Innocuously Important Episode: While mostly a standalone episode, Nathalie's actions at the end Fore Shadows a huge revelation much later on; Her decision to pass off Marinette's gift to Adrien as Gabriel's shows how little she cares for anyone outside of the Agreste family. As "Catalyst" will show, the rest of Paris can go in the thresher if need be.
- Moment of Weakness: Adrien takes a few minutes to enjoy the party that the Bubbler has thrown for him, since he's never been to a party, and Marinette in Ladybug form uses her Lucky Charm to get him away from Chloé, then takes time to sign a birthday present she gave to Adrien. As both heroes realize, they gave the Bubbler an opening to start spiriting away dissenting partygoers.
- Motive Rant: The Bubbler gives one when he traps Ladybug and Cat Noir in a bubble, talking about how adults are oppressive and don't care about their children having fun.
- No Good Deed Goes Unpunished: Nino arguing on Adrien's behalf for a birthday party leads to him getting corrupted and turned into an akuma.
- Pet the Dog: Subverted. Adrien thinks the handmade scarf he received was from his father, but it was actually from Marinette.
- Stepford Smiler: The kids being forced to dance and be happy at the party.
- Strictly Formula: Averted, being so far the only episode where Marinette uses her Lucky Charm for Mundane Utility, as well as using another one to defeat the villain later. More unusual in regions where it was the first released episode. Marinette and Adrien are also much more grave during their transformation sequences considering what occurs in the episode.
- There Are No Adults: The Bubbler tries to enforce this.
- Unusually Uninteresting Sight: Yes, kids are forced to go to the party, but Chloé still takes the opportunity to hit on Adrien and Alya still helps Marinette sign her gift. Marinette and Adrien decide to follow the lead as detailed above.
- What the Hell, Hero?: Tikki chastises Marinette for using her power for selfish reasons.
- What You Are in the Dark: Marinette lets Adrien think her present is from his father because of this.