The only reason that the Host and Soldier became friendly is because of Sugarbean. Soldier desperately wanted to pet/hold Sugarbean. But, while Sugarbean doesn't like anyone, they can't stand any of the Mercs. (Except Pyro, though they still don't like them.)
Sugar owes the Host a debt for finding them and taking care of them despite their bad attitude. And that repayment is Sugar's protection and tolerance. Sugar and the Mercs first meeting also wasn't great with Sugar mauling Heavy to give Host an opening to escape. So while Host isn't in any active danger, Sugarbean isn't getting friendly with anyone. Much less letting anyone pet them. The only reason Soldier hasn't gotten mauled is because Host stops them.











