Raelynn would act as Gregory's mother until her disappearance. He's still sick from Rabbit.py, but as long as the virus is quarantined GGY is good as gone.

Due to abnormalities and alterations in Gregory's genes, he has extra teeth and is able to contract or dilate his pupils on command. This is equivilent to messing with the brightness and gamma levels in-game.

Raelynn's therapy office was a part of the house, and Gregory saw Vanessa often when she came in for her sessions. Vanessa was the last client Raelynn had before going missing which is the source of Gregory's fear of her. He ran away from home shortly after, convinced that Vanessa would come back to finish the job.

Gregory keeps all of his possessions in a Pizzaplex duffel bag, including a folded up cardboard box big enough to hide in.

In actuality, GGY killed Gregory's mother and Gregory simply doesn't remember. Nobody involved knows enough to tell him the truth.