[It was easier for his demons to plague him when he was stressed, fatigued or frustrated. In this case he was all of the above. All he could see was his smug brother, sitting across from him, grinning behind those glasses and taunting him. Talking about how they'd steal the girl now that she was home and he wasn't there.
They'd be able to tell that the Haine that IS there was a copy. He knows it.
This sort of episode tended to happen in public but unfortunately for Haine it just so happened that someone was actually watching him. And paying very close attention. Reid would see that he seems agitated, like one would be if someone were berating you loudly. He was rubbing his temples, partially shading his eyes and refusing to look up. Trying to ignore it.
But clearly something was said to finally snap him out of it.]
Shut up! [Very pointedly at someone who clearly wasn't there at all. He knew that. He knew he wasn't real. Couldn't be in the dome.
He breaks out of it to look at Reid.]
I'm fine. [Sweat on his brow, he looked strained and tired.]