It seems like the two Fey queens have differences that extend a little beyond just their looks.
Seems the one with dark hair is rather hotheaded while the one with light hair is more of a silver tongue trickster.
Though the word exchange might be something to be of a concern. Though having magic might increase ones life span, the queen still probably can't live forever and though the queen can obviously hold her own, she is probably the only real thing hold these two courts back.
It's not quite like that.
The Fae have a treaty with her. If she's dead, the treaty becomes null and void, and they can prey where they like. Anyone who took over from her would have to re-negotiate the treaty, and would be unlikely to be as strong-willed as Moraine. (Although, there is every chance that, given time, her grandson might be capable. He just needs time to grow up.) So from their side, a quick attack and they get many years of partying. If it fails, no foul, no loss.
So, a win-win, from their perspective. From Moraine's, she expects them to be tricksy. Hence the (apparent) shield that blocks the incoming flames. I expect she'll raise one eyebrow and say something like "Are we finished with these games? I have more important things to attend to, if you want to reschedule. For another 7 years." or something. You know, the usual bravado, mixed with insane double-thinkery that goes with facing down one of the Fae. *grin*
... Can't wait to see what happens next. ;-]