This one is set after Season 2, Episode 11, Adrift

xoxoxo


Gwen walked into Jack's office after filing all of the missing persons back in their rightful place. He wasn't there, so she sat on his desk, waiting. He had seen her go up there, and, after a minute, took a deep breath and walked in himself. He always dreaded talking to her, now that she was married. He knew that he could never have her now. He had missed his chance with her. And it was killing him inside. He closed the office door behind him and smiled at her.
"How you doing Gwen?"
"Oh, fine. You know me, Jack. Brush myself off and carry on."
He saw a small tear drift down her cheek. It killed him to see her upset like this. He took her into his arms and soothed her.
"Shhh."
Gwen buried herself in his arms, snuggling into his chest.
"I'm sorry. I feel useless, Jack. We couldn't help Jonah. We couldn't help any of them. And now, I've passed this feeling onto Nikki."
"It's not your fault, Gwen."
"Of course it is! If only I'd listened to you, Jack. You were right. I shouldn't have told Nikki. It was better when she still had hope."
Jack smoothed her hair and held her close.
"You were only doing what you thought was best."
"I don't know what's best for anyone anymore. Since I joined Torchwood, I've changed so much. I can't be there for Rhys properly; I can't do normal stuff, like marriage and kids. I can't give him what he wants..."
"Hey. Of course you can. You married him, right? And you've grown so much since you joined Torchwood. It changes us all. It's just whether it changes us for the better. And it has changed you for the better, Gwen."
She smiled and allowed him to calm her for a moment, before realising that she was supposed to be apologizing to Rhys for her attitude towards him over the last couple of days. She pulled away from Jack, muttered something about Rhys and made to leave. Jack almost let her leave before pulling her back.
"Jack, what - "
Jack pinned her against the wall.
"I have to say this, Gwen."
She breathed deeply, calmly.
"Get off me, Jack."
"It should have been me."
"What?"
"It should have been me you married, not Rhys."
Gwen stared for a moment.
"Jack, I can't deal with this..."
"I need you to hear me out, Gwen."
She nodded, sighing, and he loosened his grip.
"Rhys has always been there for me," she began.
"So have I, Gwen. I've always been there to pick up the pieces after you and Rhys have argued. I've always been there after a hard day at work, comforting you when Rhys couldn't."
"You're my boss, Jack. You had to do it."
"No, I didn't. You think I did it for Owen? No. Only you, Gwen."
Gwen paused for a moment.
"Rhys isn't afraid to tell me he loves me."
Gwen felt a sensation of deja-vu, as Jack put a finger to her lips and stroked her hair, just as the Shapeshifter had done at her wedding. This time, instead of going to attack her, the real Jack kissed her softly.
"Neither am I, Gwen."
She shifted slightly, but didn't move from his arms. He pulled her closer and went to kiss her again, but she shifted.
"Rhys..."
"Forget about Rhys. Let me have one night with you. Please, Gwen. I need you."
She didn't reply with words. Instead, she moved closer to him, and softly pressed her lips to his. He softly kissed her back, shifting slightly, pulling her closer to him. She moved with him, her hand wandering over his muscles, exploring every inch of him. He did the same to her, hands wandering under her shirt to her bare, warm skin. She let out a moan as he touched her, a moan which turned him on more than anything. Gwen knew that it was wrong, but she knew, deep down, that she wanted it so much. More than anything, she wanted Jack to love her. She noticed his hands grasping at her clothing, and ripped off his shirt before he could move. He grinned at her before kissing her again, only parting his lips from hers to lift her t-shirt over her head. Jack pressed his body into hers, and Gwen gasped as she felt his arousal through his trousers, calling to her. She held him close to her, and ripped his trousers off before he had even started to unhook her bra. He moaned, her impatience turning him on even more, and quickly ripped off her bra and jeans. He stood back for a moment, examining her near naked body, before lust and arousal took over, and he once more pressed himself to her, ripping off both items of restricting underwear in the process. She leaned back against the window of the office and took his arousal in her hands. She moaned at how large and hard he was. He resolved to kiss her neck, his free hand wandering down her curves before reaching its destination. He moaned her name as he felt how hot and wet she was.
"Oh, Gwen! I want you! I need you!"
She moved her lips closer to his ear and whispered to him.
"Take me, Jack."
He didn't need to be told twice. As soon as the words had left her mouth, he had lifted her off her feet and was pinning her against the window with his weight. She wrapped her legs around him tightly as one of her hands reached down for his arousal, guiding him into her. They moaned together as he started thrusting into her slowly, finding a slow, deep rhythm which suited them both. Her hands were in her hair as he started suckling on her collarbone, both of them moaning to each other softly.
"Oh...Jack...yes, right there...oh, yes..."
"Gwen...oh...I love you..."
A few moments later, they came together, moaning each other's names, Gwen's hands knotted in Jack's hair. For a few moments, neither of them moved. Jack kept Gwen pressed against the window, just enjoying the feeling of being inside her. Gently, reluctantly, Jack lifted her down, placing her softly on the ground, his arms still around her waist, pulling her close. She gave him one last, deep, long kiss before grabbing her clothes and rushing from the office. As Jack sat down in his chair, staring after her, he smiled to himself.
"That's enough."


Not really very steamy, but I hope that I conveyed everything I wanted to!