Maybe it's just because I read The Mists of Avalon too many times and remember how bitterly Morgaine as protagonist (note Bradley's spelling of "Morgaine" is just "Moiraine" without the first i and with a g added) resented being seen as a wode covered munchkin (i.e. small and blue in addition to her mystical powers.) Moiraine says after Rhuidean that she considered bedding Rand to gain a lever on him, but her trip through the ter'angreal showed her that every time she did "the result was disastrous." The MoA version of Morgaine, unlike in most versions of Arthur, slept with Arthur because it was required of her in her Maiden-High Priestess role, but it's clear her greatest motivation was that taboos aside she wanted him. In every version of Arthur the result is the same whatever the motive:

Morgan sleeps with Arthur and conceives Mordred as their child, so that Arthur feels obliged by paternal duty and guilt to accept him as a knight and tolerate his treason until it destroys Camelot.

Moiraine is one of the best examples of Jordan "what if...?"ing tropes in general and Arthurian ones specifically. Like the classic Animaniacs episode where a computer shreds the script and produces things like "Mindy and the Brain" and "Rita and the Rat" ( "Hey, Rita, what do you want to do tonight?" "I dunno... EAT YOU?!!!" ) In this version Morgaine and the Arthur trope are close allies and ultimately friends instead of mortal enemies. Unfortunately that kind of thing can make it very hard to track who's who, and even when you're sure a given Arthurian character will do a given thing because every version of the Arthurian Cycle is written that way, you never know when Jordan is going to do a 180 on you and imprison Morgaine in Merlins impenetrable cell just so he can rescue her, or marry Guinevere off to Gawaine and Nynaeve to Lancelot (whom she's imprisoned just as effectively as she did Merlin, just differently. )