Time to relax a little again. Danger dodged for now.

"Yeah, it would just turn into more fire. Eventually I learned to control my emotions not to be a totaly chaos all of the time." Not that the control over his emotion shows anytime Eren's around. Reiner also happened to see the not controlled side. "Of course mow that I no longer need to worry about causing a havoc I don't have a total control anymore."

Which is better than actually being careful about setting something on fire anytime he stubbed his toe, for example.