She had been beaten by him once but it wasn't an official duel. She lost the duel. And it probably didn't occur to them to tell him. He was their first human visitor in hundreds of years, to them it probably wasn't worth mentioning until after the fact - "Oh shit he drew his sword" and "Oh shit, he doesn't understand our rules". You're either not paying attention, not thinking about it much, or just trying to find ways to justify a point of view that has no relationship with reality. And again, they would have been within their rights to just kill him as soon as he arrived. He wasn't invited, he wasn't an official emessary, he was told before he left to see Medb that his best bet was to just turn around and go home. If you really want to hate the Alfar that's fine - but they haven't given MC any real reason to hate them. He did a stupid thing by going to visit them, he was warned that it was a stupid thing to do and did it anyway - and then was saved by his own actions (unless you decided to play it especially stupid.)
First of all, I don't care how alien the Alfar are, the idea that the only way to refuse a duel is to let the aggrieved party kill you is asinine. Sure, Finnabair would technically be guilty of murder if she didn't pull her punch at the last second, but it would be a little late for the MC to care about it at that point. So right off the bat the Alfar's legal system is already on the thinnest of ice possible.
But beyond that, you cannot have it both ways: if the Alfar are such a litigious society that assaulting someone under a flag of truce is acceptable the instant his protection expires, then they're also litigious enough to recognize that the MC's verbal refusal to duel is in fact a refusal to duel - or at least tell him what else he needs to do to make that refusal formal. Medb - and Ailill - did no such thing. They were happy to turn a blind eye to his attempted refusal and allow the challenge to hang around until obvious happened, at which point it was tragically too late for the duel to be stopped.
Sorry, I don't buy that this outcome could somehow come as a surprise to them. And again, the letter of the law suddenly got *very* flexible AFTER Finnabair spectacularly failed to kill the MC.
Lastly, if you consider turning a blind eye to attempted murder then arresting the MC when he manages to defend himself "no reason" to hate them, I don't know what to tell you. I finally played through the "kill Finnabair" branch, and frankly the notion that the elves have the unmitigated gall to not only detain him but to tell him he should "be thankful [he's] still alive" for something they FORCED him to do is, in a word, outrageous. [EDIT : Oh right, I forgot about the interrogation and death mark; they did that, too!]
I agree the MC was stupid to go to Alfheimr (though I dispute that he was told it was stupid to go there; Kari implicitly told it was a good idea, AND explicitly told him that the Alfar would not be a great danger). But just because it was stupid doesn't mean it's suddenly okay to kill him for it, much less punish him for refusing to die like a nice victim. I'm asking sincerely: if the Alfar haven't done enough to earn his ire at that point, is there anything the Alfar could have done that
would justify hatred?
