Eren's hands reflexively ball into fists, nails scraping against metal. While he was certainly angry before it's a hundred times worse now, to the point there's a look of murder in his eyes. Thankfully it is not, however, directed at Cairbre. Something Eren soon makes clear.

"So it was Devil! Why is it every time Armin gets hurt, that fucking son of a bitch is involved somehow! I'll make that bastard pay for what he's done to my friend!" Never mind that he has no idea how; he has no idea what he could possibly do against a being as powerful as an Arcana. That doesn't matter to him right now though. Eren's come a long way while Traveling but he still has a Titan-sized vengeful streak, and it's that anger that's talking right now.

Still, just because a lot of Eren's rage has been focused on the Devil doesn't mean he's stopped also blaming Chariot just yet. "Even if the Chaos wasn't supposed to be there, it was still a place that tried to drive us all insane! It did drive my friend insane, before the Chaos ever showed up! Why did the rest of you let Devil and Strength send us there in the first place!?"