Leon's your older brother, only 2 years older than you. When you were 3 -- and Leon was 5 -- your parents gave you both away to Umbrella, financial complications. It was just so startling and formidable.

Years have elapsed, and you both grew up in the labs, abused. You both stayed jointly, in an empty, bland room, taking an identical amount abuse in.

You both didn't do anything do deserve this fate, but you learnt to accept it. Devouring bugs and getting experimented on.