Cutie Mark: A lightning storm. He makes storms which have the unique ability that if anyone or anypony walks into their eye their deepest, and sometimes darkest, memories are pulled forth from their subconcious. Whether they are good or bad memories depends on the pony, but they are never direct, hence the pony feels a sense of Deja Vu. Which is where his name comes from.
Personality: Hes alot like his twin sister NightShade, except that he is alot more outgoing, in the more direct sense of the word. He is highly misunderstood because of his powers tendency to draw out the most painful and tragic memories of ponies pasts who enter his storms. He is highly seen as evil, but he really isnt, hes just tragically misunderstood.
Backstory: Deja has been locked away since birth, much like your stereotypical princesses(except hes a boy), because the ponies in the village he is from beleived that his talent made him pure evil. His twin sister has no idea he even exists, and his terrible upbringing has taken its toll. He has a tendency to be a little too serious for his age and secretly he is easily hurt. His goal is to find his sister and just to be acknowledged. His odd talent is actually a curse, which will eventually be realized as a gift.