[He doesn't really want to join. At all. He's not a... 'joiner' in general. Leading something, that's different. But the last time he followed anyone, well... that had been a few centuries ago and he sure as hell hadn't enjoyed that. And if he were back in Amestris, where he knew the country, where he had his Shield, where he knew what he was doing? He'd say no.

But they weren't in Amestris, now were they...]

...guess that's not that bad of a deal, all things considered. So what the hell, why not. I'll join.

That is... assuming you don't mind someone as questionable as me in your ranks.