Merlin quirked a brow at the statement. Really, now? For someone who knew it, he'd reacted rather badly. Arthur didn't act like he'd known the truth. Not that he'd say so. Merlin figured arguing would just instigate another bout of anger.
"Too be fair...I did confess." He pointed out. "When Gwen was -- I made the poultice. I had been telling the truth when I said I made it. I couldn't just let her father die..."