As I see it, Jack's there for Sam and Teal'c. But when they tell him to back off (Morpheus, Ascension), he does. With Daniel, he doesn't back off when he's told. Might help if I could think of examples, but I'd have to rewatch the whole series because just absolutely nothing concrete is coming to mind.

But it's just my sense of it anyway - I don't expect others to see it the same way or anything. :)