Are we supposed to be using spoiler code to hide posts in this thread? It seems a bit over the top since no one should be in this thread not expecting them.
Yeah, Celene personally wouldn't be concerned Michel had an elven mother, I mean she had taken an elf as a lover herself. She could possibly have been concerned that someone could use the information against her, but again, the elven lover issue would seem much more scandalous and because he looks very human it would be extremely hard to prove. She might have been perturbed that Michel had deceived her, but I doubt it. Of course it would be Michels perception of this because it was his decision.
I considered the fact that he simply didn't want to kill Gaspard and so he used his honor as an excuse. But I would have misread his entire character in that case. He was imo very honorable and he made the decision simply because he was honoring his promise to Briala even though he didn't want to. But as I said above, that doesn't make sense to me because he is simultaneously breaking another, imo more important, promise.