Dark Riku

Dark Riku is Riku Replica's time traveling heart in a new replica body. He was collected by Young Xehanort to serve as a member of the real Organization XIII.

Kingdom Hearts 3D: Dream Drop Distance
In Monstro, Riku finds a figure in a black coat walking with Pinocchio. The figure acquiesces to Riku's order to release the puppet, and lowers his hood when Riku demands to know who he is—revealing a face identical to Riku's own. The doppelgänger quickly disappears through a Corridor of Darkness before Riku has a chance to pursue, and Jiminy Cricket asks who the boy was. Riku says that it was his dark side, and he mentions the "imitation that was copied" from his darkness.

Later, Dark Riku appeared alongside his fellow members of the real Organization XIII at Where Nothing Gathers. As the heroes advance, the Organization's allotted time expires and its members, including Dark Riku, retreat to their rightful points in time.

Appearance
As Riku's replica, Dark Riku is identical to the real Riku in nearly every way as he appeared in the first Kingdom Hearts game. The most discernible difference between them is that Dark Riku has yellow eyes like the rest of the real Organization XIII, as opposed to Riku's aquamarine eyes, indicating that he harbors a piece of Xehanort's heart within him. In his initial appearance however he possessed the same eye color as Riku. He primarily wears the Organization's black coat, while also periodically shifting into his Dark Mode form at the Keyblade Graveyard.

Personality
Just like in Chain of Memories, this version of the Riku Replica considers himself to be the "real" Riku, and his superior. He behaves exactly as the real Riku did when corrupted by darkness, being arrogant, cruel, and remorseless. He also allows Sora, Riku, and his friends to believe that he truly is the real Riku's past self from when he was possessed by Ansem.