<Snipped quote by CaptainManbeard>
I see. Probably something time related, precognition and general temporal manipulation, since I have a character arc idea where a future version of my character from an alternate timeline intentionally corrupted the Quantum Shard they had to become a Void Demon, as they seek to stop the mending of the crystal to preserve not only their own power and/or existence, but also to keep what they see as the loop within a loop from repeating. I.E. to keep the crystal from being reforged just so another group of gods or beings, be that the Avatars or whoever else, can go to war over and shatter it again. This antagonistic future version of my character would also seek to maintain the status quo as it currently is, believing that all the realities which presently exist thanks to the shattering will be erased or destroyed or irreparably damaged if merged back into a single timeline.
And that's not a risk they're willing to take.
I had a similar idea for my Sith character XD. I was thinking of making them eventually become an evil character, and she is an alternate timeline version of my good character's twin sister. They come from very similar timelines that split off at the moment of a plane crash when they were kids. In the brother's timeline, his sister died, and in the sister's timeline, her brother died. He managed to grieve and then recover, but she still harbors a lot of emotional trauma from that day and gradually becomes resentful of her alternate timeline brother for him not having been as miserable as her after losing his twin. Not only that, in his timeline, their parents had another daughter, while in her timeline, their parents divorced and then eventually died in a car crash while they were arguing. She begins to feel betrayed that the other version of her family had such a happy life without her and that sparks the gradual corruption of her Quantum Shard.
As for your idea for time powers, I'd be curious to see just how far you wanted to take them. Since the Cosmic Crystal is a fourth dimensional construct, and by extension the Quantum Shards, I'd imagine any temporal-shifting abilities would not directly effect anyone who also had a Shard. But it could effect the environment around them. As for the future version of your character, I'd imagine their Shard would be a different one than the past version, since it seems unlikely that a fourth dimensional object could go back in time and co-exist with a past version of itself. Instead, it could be that his timeline was ripped in two as well, with a different Shard going to each half and finding him in both timelines.
I have to head to work now, but we can discuss it more later. I'm excited!