Modern AU: Arthur learns that Gwen dated Morgana during her bi-curious phase in college, when he brings her around for the Sunday family dinner with the parents (Uther and Ygraine).

"Oh, my God, Gwen! Arthur didn't tell me that you were the Gwen he was seeing!" Morgana exclaims, hugging Gwen tightly with a squeal. "He always calls you Guinevere, and I never made the connection…"

"Hey, Morgana," Gwen answers, a trifle nervously, hugging her back, a little less tightly. "I guess I didn't realize you were Arthur's sister. I mean, I figured you might be related, as Pendragon isn't a very common name and all…"

"You two know each other?" Arthur asks, puzzled.

"Um, yes, we knew one another at University. Morgana was friends with my roommate Freya, and…"

"Oh, weird. Small world," Arthur says. "Come on, let's go meet my parents," he says, taking Gwen's hand now.

"Well, I hope you've already met them," Gwen remarks, inwardly exhaling that Morgana kept her mouth shut about the nature of their past friendship.

I'm going to have to tell him at some point. Surely he knows his sister is a lesbian, though…

Thankfully, Arthur's parents keep her occupied with questions about her job and her family. Ygraine is lovely and engaging. Uther is a little stoic but proves to have a very dry, sneaky sense of humor that continually catches Gwen off guard.

"Have you kept in touch with Freya?" Morgana asks suddenly.

"No, unfortunately we lost track of each other. She went the veterinary school and I went to grad school, and it just got too hard. You?"

"Well, she's just started dating Arthur's best friend," Morgana smirks.

"Merlin? Wow, really?"

"So you may be seeing her again. Perhaps the four of you could go out on a double date," she suggests. "Oh, wait, Arthur doesn't like double dates, the selfish bastard," she chuckles.

"Sorry if I didn't want to take my new girlfriend on a double date with my sister and her girlfriend, Morgs," Arthur sighs. "We'd only been dating a couple weeks, I felt it was a little early in our relationship to unleash the Gay Sister on her."

"I think I would have been okay, Love," Gwen comments.

"Well, I know that now, Arthur comments. Morgana, would you and Vivian like to join Guinevere and me for dinner some time?" he asks. "God, I just asked my sister out. Yuck."

"Don't worry, Arthur, you're not her type," Uther comments mildly, taking a sip of his wine.

Gwen gets through the evening, but she couldn't help notice Morgana's eyes on her a little more than she would have been comfortable with.

"You're quiet, Guinevere," Arthur says, reaching for her hand while they drive back to the apartment they just rented together.

"Arthur, I have something to tell you that you're not going to like, so I'm just going to come right out and say it."

"Um, okay…" he says.

She says nothing for a moment, waiting until they are stopped at a stoplight. Wouldn't want him to drive off the road.

She extracts her hand from his. "Arthur, you sister and I were lovers in college. Briefly."

He stares. She swallows, and continues.

"I told you I went through an… experimental phase…"

"With my sister?"

"Arthur, it was ten years ago."

The rest of the drive is silent. Gwen looks out the window. That's it. He's going to leave me. I just got unpacked, and now I'm going to have to re-pack. She peeks at Arthur. His face is a mask. I hate it when he shuts down like this.

They walk up to their apartment. They may as well be strangers. Gwen immediately goes back to the bedroom, flops on the bed, and lets the tears fall, clutching his pillow.

Arthur paces. He thinks about the bottles of beer in the fridge. He decides that they are a bad idea.

Finally he walks to the bedroom to find her curled on her side around his pillow. He can hear her sobs, and they rip at his heart. "Did you… feel anything for her when you saw her today?" he finally asks.

"No," she sniffs, almost petulantly, still facing away from him. "It was one week during freshman year. I thought she was beautiful and exciting. I thought I might be… attracted to her. She was already way out."

"I know. She came out the summer before she went to uni. Dad didn't talk to her for a week," he chuckles. "He's okay with it now…" he trails off.

The fact that he is rambling makes her feel better. If he was really angry he wouldn't be suffering from verbal diarrhea.

"I was young and confused. I guess I needed to learn the hard way which way my… preferences lie."

"And you decided…?"

She finally turns and looks at him. "I like penises."

"All of them?" he asks, raising an eyebrow now.

"Mostly yours," she says, her unsteady breathing hitching into a sob/giggle.

He comes over and sits on the bed now. "What's in the past is in the past," he finally declares.

"Spoken like a man who has something to confess," she says, arching her own eyebrow at him.

"Well, Merlin and I…"

"NO!"

"Kidding! Sorry, I couldn't pass it up. Though inexplicably people sometimes think that we are…"

"Well, you are rather close."

"I've been friends with him since we were five! Sheesh…"

He flops down onto the bed, curling himself around her now. "You know Elana Godwin?"

"Ew, Arthur, no…"

"Yeah. Tapped that. Not proud of it."

"Please tell me alcohol was involved. The woman is an insufferable cow."

"Of course alcohol was involved," he says, kissing the top of her head.

"Did you have yourself tested after?" she says, giggling now.

"For…?"

"Herpes, gonorrhea… anthrax, rabies, distemper, worms…"

"Those last four are diseases animals get."

"Your point?" she looks up at him.

"Shut up," he says, leaning down to kiss her now. "Ugh, mental images of you and my sister…" he groans, pulling away and pressing the heel of his hand to his forehead in an overly dramatic fashion. "Might be kind of hot if it wasn't my bloody sister…"

"Shall I help erase those horrific mental pictures?" Gwen asks, slowly sliding her hand down his chest.

"You can try," he says, trying to sound despondent.

Her hand slips inside his trousers and effectively erases any thought from his brain other than her.