Character Analysis
Guenever is the daughter of King Leodegrance, and brings the Round Table with her as a marriage gift. So, in a way, she's partially responsible for the brotherhood of knights. This is fitting, because some of her major character traits (we're told) are that she's generous, courageous and honest. In fact, if Arthur had ever just point-blank asked her if she was also seeing Lance, she would have admitted it without hesitation.
She's a beautiful woman, described as having hair "so black that it was startling" and eyes of a blue that's "deep and clear" and also fearless (K.4.16). Guen keeps her good looks even as she ages, although in the later years she kind of overdoes it a bit with the makeup and flashy clothing.
She seems to have an even greater inner beauty, since she's described as lovely, "like a woman who had grown a soul" (C.7.1). Arthur and Lancelot both call her "Jenny," and Lancelot thinks of her as "pretty Jenny" (K.4.49).
Queen Guenever vs. Jenny from the Block
Guenever behaves differently in her two major relationships. With Arthur, she's a proper Queen. She feels affection toward him, and feels lots of "gratitude, kindness, love, and a sense of protection" for Arthur. But, there's no passion there, like she feels with Lancelot. This might be because the marriage between her and Arthur was arranged, and he is a bit older than she is (she was twenty two and he was thirty when they married).
With Lancelot, on the other hand, she feels romance and passion from the first time they meet. Plus, he sends her all those prisoners to kneel at her feet, which completely overwhelms her. She goes a bit crazy-jealous when she finds out about Lancelot and Elaine, and sometimes behaves in a capricious, overly dramatic, and super-angry manner toward him.
But they end up sharing a deep love, which remains strong well after they've both turned gray.