I think damon more respects that certain people can be a danger to him than that he respects people, and that makes them more interesting to him, as long as they aren't getting in his way. With Bonnie, I think that part of it is that he seems to have had a lot of interaction with witches over the years, and is probably used to the "all witches are family" mindset that Jonas has, and is cautious about Bennett's in general. I...actually suspect Damon could stop Bonnie from the aneurisms if he wanted, now that he's used to it? But it would mean getting rid of her, or complete avoidance, and if nothing else, he realizes he's way better off with her willing to help him if he pulls the "for Elena!" card (and vice versa). I think he...generally wants to be on her good side, but also doesn't want to put out the effort.