Rah

Rah is the Universe Shard that is the center of the Milky Way, and is the source of bending.

Creation
Like all Universe Shards, Rah was created during the big bang, and its elevated energy speed created a gravitational effect on matter around it, and taking the matter with it out into space, creating the Milky Way.

Endowment
No one knows exactly how bending works, or how Rah endowed it to a string of human beings, but when Valerius Maximus bend dark energy, it was speculated that Rah is composed of an equal amount of dark and light energy, 1's and 0's in a random, ever changing fashion, like a huge computer that changed it's programming an uncountable amount of times every second.

Resurrection
Both Blake Pravo and Valerius Maximus were resurrected, and the dark and light energy theory doesn't give a satisfactory solution to why this happened, at a time of great need for a bender.