A character or an entire group gets split. It can be a small rebellion of characters thinking differently or a Split Personality of a character creating his Evil Twin. The two entities created are so completely opposite that it's hard to believe they have something in common. Then, however, they reunite. The reunion results in creating something more perfect than the original entity.
The main plot is often put in the time when the entities split. The reunion would be connected with the climax or resolution of the plot. The moment of the split would be often revealed in retrospection. Revealing this fact would be a plot twist.
Compare Break-Up/Make-Up Scenario, when the protagonists have a falling out and are separated, but meet again and reconcile in the end.
Anime & Manga
- Dragon Ball: Demon King Piccolo is a result of Kami-sama's struggle against inner evil. They live separately as foes for a time. In Dragon Ball Z, Piccolo Jr. then fuses with Kami-sama becoming more powerful.
- Something Awful: Dungeons & Dragons: Averted with Joey/Evil Joey. They never merge back into one individual.
Films — Live-Action
- The Dark Crystal: The Skeksis and urRa are depicted as completely opposite. From the first moments of the film, however, we can see some symmetries between them. Later they reunite and explain they were split beings. The official book about Dark Crystal world says, their split was an effect of purity pursuit.
- Devil May Cry 5: Due to the numerous times he lost in battle and his subsequent corruption into Nelo Angelo, Vergil is at death's door and has to split himself into two literal split personalities (V and Urizen) after impaling himself with the Yamato. In the aftermath of Mission 17, V decides to merge with Urizen again, bringing forth a re-completed Vergil who's now free from the corruption that his body suffered. He also gained new things due to the actions of his two halves; with V, it's a Character Development of interacting with Dante and Nero on a friendlier basis (which is mostly shown only after the Final Boss fight of Mission 20), while a Hand Wave from Nico's Reports imply that Vergil gained his Sin Devil Trigger form because of Urizen.
- Honkai Impact 3rd: In the 28th chapter, clone-siblings Kiana and an amnesiac Durandal re-meet to fight Otto. Even while they remain motivated by different objectives, they manage to get past their differences and fight as a team.
- Star Control: In the second part, the Pkunk are revealed as the offspring of Yehat, with Pkunk being New Age Retro Hippies and Yehat Proud Warrior Race Guys. At the end of the game however Pkunk visit Yehat, they are absorbed by them, and the Yehat elect a Pkunk as their queen learning from their pacifistic brothers some new spiritual insight.
- Lost in Blue: Subverted. The plot is about Cube helping Rave find his brother Cuda, as they got separated after arriving in a different world. It ends with the brothers reuniting the following day, but before Cuda can even meet Cube, she disappears.