Cal
Jason’s friend and a fellow associate of Brian’s, Cal feels safest hanging at home, snooping on Coast Guard comms with a few beers and some private browser tabs open.
Cal is one of several supporting GTA 6 characters working at Brian’s Boat Works & Marina. Seen initially in the GTA 6 trailer 2, Cal Hampton has been described as a friend of Jason‘s.
From what little we’ve seen of Cal, Cal appears to be an incredibly laidback individual, but the official Rockstar description of the character implies that he suffers from a “casual paranoia” of sorts.

Cal description
“What if everything on the internet was true? Jason’s friend and a fellow associate of Brian’s, Cal feels safest hanging at home, snooping on Coast Guard comms with a few beers and some private browser tabs open.”

Cal is otherwise described as being “at the low tide of America and happy there. Casual paranoia loves company, but his friend Jason has bigger plans.”
From the trailer, we can also infer that Cal is single, or at least looking for a relationship. Presumably addressing Jason in a cutscene, Cal asks “hey, if you got friends, can you hook me up please?”
Cal‘s known associates: Cal‘s known relatives: No known relations