Danny's absolutely like a lost little boy, which is why perhaps he's not much of a support to anyone. Danny's emotional and needy, and let's face it, Flack is by far the stronger of the two. If Danny had been hurt in that bombing, Flack never would have left his side, and afterwards, Danny would have complained and whined and carried on for months. Flack is just the more stoic sort.
I think Danny and Mac are definitely opposites, so I'm intrigued to see how their relationship will evolve in the third season. I'd like to see more of the conflict between the two that existed in season one!