Maureen was revealed to be pregnant at the end of the comic "Portrait of a Football Player", and was eventually born in the next comic, "Wouldn't It Be Nice?". He is the sixth and officially the last sibling of the McReary-Wilson family, being even younger than Kate (who had been the youngest sibling since 2006).
Aiden has many differences compared to the original five McReary siblings; Aiden's father is not Mr. McReary (although Maureen named Aiden after him), he wasn't born in Vancouver, Canada, and although he still has McReary in his full name (it is his middle name), he uses his father's last name, which is Wilson. Aiden is also the only sibling to be blood-related to the other Wilson family members (such as Louis's children), as they are only step-relatives of the McReary siblings. Aiden is not considered to be a part of the five McReary siblings, and he will not appear in every comic like they do.
Aiden has been retconned from the franchise following the fifth season. He did not appear in the short-lived sequel series Sibling Rivalries: The Next Chapter, nor will he appear from the sixth season of the original series onward. This makes his birth non-canon, and even though the comics that he appeared in are still canon, the scenes he appears or is mentioned are now non-canon.
As a baby, Aiden wears uncolored pajamas with a visible zipper, and he has four small hairs coming out of his head. As an older kid (he appeared like this throughout "ApRiL fOoLs DaY: wIsCoNsIn StYlE!"), he wears a polo shirt with sleeves and the number 1 on his shirt. He has curly hair and basic shorts, socks, and shoes.
Aiden's name is similar to that of his older cousin Adrian Wilson. The name Aiden was given to him because it is an Irish name; Maureen named Aiden after her first husband.
Aiden is similar to the character Dil Pickles from Rugrats. Similarily, Aiden's older cousin (and Adrian's younger brother) Troy Wilson's personality is based off of that of Dil Pickles as he appears in the Rugrats spin-off series All Grown Up!.
With Aiden's introduction, the comic series now has characters that are based off of both of Dil's appearances in the Rugrats franchise.
Aiden is the youngest character in the entire franchise, being even younger than Rose Parker.
Aiden is the last addition to the series's main cast.
Aiden has suffered the same fate as Sparky from The Fairly OddParents, with both being written out from their respective series after a season or two due to bad reception.