[Goddammit. Well, he'd keep his word, if mainly just for more recent events.]

...I'm afraid Gaius was abducted by someone in league with Morgana, not so long ago. He was tortured, for information. More recently, he was left to starve in the dungeons when... Camelot fell to Morgana. Temporarily.

[Lots of details left out, he knew, but he didn't especially want to go into them. But he at least owed it to Merlin to let him know how Gaius was doing.]

But as I said, he's fine now. Both times he was rescued before anything worse could happen to him.