Character Analysis
Morgause is the self-absorbed, narcissistic, self-indulgent Queen of Lothian and Orkney. She's married to Lot (until he's offed by Pellinore), and is the mother of the G-boys. She's also a sort of witch (poetically referred to as The Queen of Air and Darkness), although not a serious one. And she's not smart enough to be a serious one, either. Her "head was too empty to take any great art seriously" (Q.1.51). Most of her witchcraft is done out of boredom; she wastes time while the men are gone by dabbling in magic.
However, she very much "wears the trousers" in her family (Q.3.41), and exercises a kind of hot n' cold, loving n' hating, maternal n' sociopathic power over her sons. Lancelot describes her as a "bad old woman" (K.26.15), Arthur refers to her as "that woman," and she's known as the "queen-witch" (K.27.1).
Be afraid. Be very afraid.
World-Class Seductress
A great beauty with black hair and blue eyes, Morgause is quite the man-eater, and is particularly interested in younger men. She's old enough to be Arthur's mother when she seduces him (with the help of her handy dandy Spancel, a disturbing piece of magic that's made out of the skin of a dead soldier). She's also old enough to be Sir Lamorak's grandmother (she's 70!) when she shacks up with him.
But lest you think that this cougar-style vamping is awesome, remember that all this seducing definitely comes back to haunt her. Her fling with Arthur results in the birth of Mordred (who is bad news for just about everyone) and she shortly after loses her sons to Arthur's court.
And she loses her head—literally—when her sons find out she's with Lamorak. Yup: Agravaine cuts it off. At least she died the way she lived: in bed with a young dude.