[Jean looks down, at his shoes or something other than Reiner.]

... I thought I was a Warrior too. Nothing else came across my mind. Just the dread of needing to kill my enemies.

[That feeling wasn't just easily forgotten. He slowly wraps his arms around himself for some comfort. Suddenly he feels kind of cold, but he doesn't bother using his powers to up the temperature.]

I get it now. The pain you were all in when you had to fight us. When you knew you had to one day kill all of us. I felt it. It probably wasn't even a portion of what you went through. Hell, I don't think I could handle any more than what the dream gave me.

[If he had been 'on the other side' he wouldn't have had a choice but to handle all of it somehow. He understands the fear of not being able to do that now, too.]

Your life has been hell.