Someone in the comments section on that flashback link made an interesting prediction... that Kylo Ren is a Ezra Bridger from Rebels...
being that Kylo Ren is rumored to be a collector of artifacts, which Ezra does... it would at least give us an idea what happened to him (as he has know known whereabouts in Episode IV...
As another poster pointed out, he does like his unconventional lightsabers...
I think it would be great if true... I nice fall from grace story done better than with Anakin... Rebels is already showing that Ezra has issues controlling anger...
And now that I LOOK at Ezra... he could be a young Adam Driver... I like it.