Talk:The Fires of Idirsholas/@comment-5674726-20131126001344/@comment-5102537-20131127141205

Yes, it was irresponsible. Even though it was part of Merlin's (earlier) character and nature to keep a promise, this wasn't the only time that he acted irresponsibly with a certain selfishness. His later compulsion to only to protect Arthur, come what may, and the earlier deal he made with Nimueh emphasized that he was indeed willing to sacrifice others for his own goal. Here it was potentially saving his mother.

I would grant him the assumption that maybe Kilgharrah would spare Arthur and innocents since the dragon had always told Merlin that Arthur must live at all costs. Maybe Merlin thought that Kilgharrah would take revenge on Uther and was willing to let it happen in order to not risk his mother's life.