I don't have anything too interesting to the masses likely so I am so sorry but in one of my friend groups we kinda just convinced ourselves that he's part Italian. I wish I could remember why but I'm genuine about it lmao maybe it was a joke about his hand usage

Something deep; Actually we did have some made up lore about his family, something about Mac and Terrence being half brothers or something. Something about Terrence having vitriol against Mac for that / their situation with their dad LOL (besides having an imaginary friend)

I always pictured him growing up to be either a neet or a tad bit of alt fashion for some reason. Sounded funny to me with the contrast. Definitely would have suspicious magazines Bloo would taunt him over. He'd still be as intelligent and voice of reason as ever though >_>