And mine is a toss up between two.
One, a human artificer. Atomsk model psiforged EB-01 had a good life of being a war machine, becoming somewhat powerful and successful. Then, one morning, he wakes up in Sharn feeling groggy. Except warforged should feel neither groggy, nor asleep. Realizing he has no memory of a rough month period, and that he cannot figure out why he is human, he has taken up the only work he knows (machinery) in an attempt to recreate his body, hopefully to unravel his mystery. He remains in Sharn, the city where he woke, hoping to hunt down the reason behind his mad transformation.
Human Artificer, probably dipping into Renegade Mastermaker. Think Edward Elric meeting Tony Stark.
The other, a warforged. Echis Bell was a man dedicated to his craft, of unravelling the mystery of the warforged. His hobby took a turn for the more serious one day when he activated one morning, to discover himself turned into one. This wouldn't have surprised him, as he was both often drunk and contemplating his transformation... except that the machine he became was far more advanced than anything he could have built, his laboratory, when he returned, had been destroyed, and his memory cuts out a month before. Pleased with his newfound powers, but eager to discover what happened to his real body, Echis Bell works through Sharn as a bodyguard, trying to unravel the mystery of his transformation.
Psiforged Psion, probably kineticist, going Slayer. Fun, has power, but isn't too broken; I dun like playin with teh broken toys. Think the ironman suit, but sentient. Danger will Robinson!..... just kidding....