Sharing some of my personal headcanons:
Skid is allergic to cats, which is why Lila refuses to get him one when he was asking. Also the reason he does not like cats
Dexdoll would get Pump in trouble on accident when they stole crayons from Susie’s room so they could write the papers we see in that one QR code
Radford smokes when stressed, which is a habit he picked up from John. This became worse when Hope went missing, especially since he was the one who was taking care of her that day
Pump likes fireworks but is afraid of the noises that they make. Susie has noise-canceling headphones, but he’s doesn’t want to ask her for them
Lucky likes pinwheels and attaches them to their hat
Dexter likes taxidermy (specifically ones involving bugs) and would gift some to their mother
Robert has a collection of gemstones he gets from museums or tourist sites, which he shares with his little sister
Carmen and Richard sometimes like to wear articles of each other’s clothing
Roy secretly has a book filled with pressed flowers in it. Only his friends (and his parents) are allowed to know, since they gave him some of those flowers