Fan:Digimon AA

Digimon AA, also commonly written as Digimon Double-A, Digimon Alternate Adventure, or unofficially Digimon Adventure 03, is a fanfictional Digimon series & partial sequel to Digimon Adventure & Digimon Adventure 02. The series focuses on a group of alternate versions of the original DigiDestined in the first seasons, similar to the video game Kingdom Hearts II.

Plot Summary
Taiji & his friends have no idea where each of them came from or who they are. That is until they travel to the Digital World, where they meet their own personal Digimon partner who need their help saving their home from a new evil. While in the Digital World, Taiji & his friends learn that they're actually alternate versions of the DigiDestined & why they shouldn't have existed in the first place.