God, it is like this unholy blend of the odd couple, the two old Muppet dudes and second-grad pigtail pulling. Plus sexual tension. Tatsumi does this thing where he'll be kind of a dick, in an impersonal sort of way, but, on a whole, professional when dealing with people in general... but he's just. A terrible person to people that he likes. Unless they're very much kindred spirits who are more sort of commiserating chums, he just... gosh. Seems to show affection by mocking, bullying and trolling people as much as he can. And then cooking dinner for everyone or something. IT'S SO EMOTIONALLY MATURE.
I think that Tatsumi sees Dante as being like a co-worker, though in that loaded Yami no Matsuei sense of "co-worker," where it becomes this funny little family-esque sort of thing that is sometimes not all that close but also sometimes kind of incestuous. And that's really... a comfort to Tatsumi, because he was working as a shinigami for, like, half a century and then that predictability was suddenly gone and now there's the possibility of never going back to it and the future is terrifying if he thinks too hard about it.
Re: random icon
I think that Tatsumi sees Dante as being like a co-worker, though in that loaded Yami no Matsuei sense of "co-worker," where it becomes this funny little family-esque sort of thing that is sometimes not all that close but also sometimes kind of incestuous. And that's really... a comfort to Tatsumi, because he was working as a shinigami for, like, half a century and then that predictability was suddenly gone and now there's the possibility of never going back to it and the future is terrifying if he thinks too hard about it.