Born as an unwanted child to an underaged, drug addicted e, Zelo has always been around more bad people than he could count. The moment he was old enough and lost his childishly plump body, his 'mother' sold off his ity to the highest bidder. From that day on, most customers came for him. When the that bore him died, he continued on, not knowing anything else than what he already did. He got used to the pain, even grew to enjoy the forced pleasure. Even though that might have had something to do with the amount of drugs and alcohol he consumed on a daily basis.
He had killed his first victim when he was 16, the man recognising him as the bastard son of his friend and threatening to turn him over to the authorities. The thrill he got from murder quickly replaced any artificial high drugs could give him. Three years later he got caught, with a headcount of 47 dead and jagged beyond belief.