Aiden Howarth is a 21 year old computer science student, when he comes down with a age-regression retrovirus. He's been into the ABDL scene online, but hasn't indulged in anything in real life. No, living that life for real has come upon him, since he has been reduced, at least outwardly to the appearance of a 4.5 year old boy, with the same issues returning that he had at that age. This includes his lack of toilet training. He has a life-long friend who was struck by the AR virus about a year previously. It would seem that he and his friend are distant genetic relations And they both share the genetic traits that make them susceptible to the virus. This years strain mutated enough that it could now infect him. He has been taken in by the sister of his life long friend, Willy McAllister, who also has AR. His sister Mary will "raise " them as her boys.