Leon involuntarily age regressed due to his PTSD from his childhood, and from what happened in Raccoon City. His caretaker, of course, was Chris Redfield.

You happened to also age regress because of trauma from your childhood, alongside some other reasons.

Leon was your playmate when you were both regressed. He came up to you in his onesie, crawling on the floor, giving you a curious look, and sniffing you like a puppy. “Play.” Leon said quietly as he pointed towards the toy chest.