In my case, both Sin and Marduk were considered the heads of their respective pantheons at some point, so they might have the whole leadership thing going for them. Maybe they're the head of a highly successful company, with their human personality being a hard-assed near-psychopath to get to that position, which naturally conflicts with their own deific personalities - Sin's perhaps more debatable on this topic, but he covers wisdom, so I'd assume he's quite friendly to most, whilst from what I'm reading about Marduk, he's almost certainly a good person given his battles against entities such as Tiamat, though perhaps inclined to be good at combat in various ways, so there's that. Hell, maybe I make both of them to start with, and they're the heads of rival companies, even... something like that, if I can actually roleplay a company leader effectively. As for Kur... I got nothing. Maybe something to do with indomitability, since he's apparently representative of the land and/or mountains. With that in mind, you said "mortal forms" rather than explicitly "humans" in the first post; would it be reasonable to make a character that starts off as, say... a lizard of some form? Probably not, but I'd just thought I'd bring it up as a fair point.