Duo and Scythe are way more casual, but that's because Duo hasn't been in danger around Scythe yet, so he hasn't had any reason to go juggernaut of flaming death on people or all possessive/worried, either. XD

Duo wanted to know if Heero would put his pride first, or his dragon. I mean, they're here to fight a war, he knows there'll be times where it's inevitable that he'll have to ask Scythe things that will injure him or risk killing him, but here it's not inevitable at all, so if Heero was still all "fuck you I don't need anyone's help" he'd know he doesn't want to associate with him for sure.