WARNING: End of Time spoilers :(
"I'm sorry, but I can't come."
Ianto asked, "Where will you go?"
Fenn looked at the crowd milling around the train station, "Home."
"You're a genius. You're stone cold brilliant; you are, I swear, you really are. But you could be so much more. You could be beautiful. With a mind like that, we could travel the stars. It would be my honour. Because you don't need to own the universe, just see it. Have the privilege of seeing the whole of time and space. That's ownership enough."
"Would it stop then? The noise in my head."
"I can help."
"I don't know what I'd be without that noise."
"I wonder what I'd be without you."
"Where's home for you?"
"I have a little place, just out of Edinburgh. It's cosy, and I know people there."
"Family?" Jack asked.
Fenn just looked at him, and then turned away, "No."
Jack fell silent, and they stood on the platform awkwardly whilst people drifted past, oblivious to them. An announcement came over the loudspeaker letting them know that the train to London was just around the corner. Fenn turned to the two agents, "Well, I guess this is goodbye."
"But really, do you think I'd leave my best friend alone without a defence mechanism?"
Jack pulled a card out of his pocket, and an envelope. "Here," he said as he handed them to Fenn, "Consider yourself an associate of Torchwood. You're not technically part of the team, but if you ever need us, just call."
Fenn took the two objects. The card was a government clearance pass, which allowed access to the majority of sealed government systems, and also provided other perks like free travel on public transport. The envelope was sealed, and on the front was written in what looked like the Doctor's handwriting, "Fenn". She put them in her coat pocket and nodded to Jack, "Thanks."
"You've got six billion pairs of eyes, and you still can't see the obvious, can you?"
"That guard is one inch too tall."
Then it was Ianto's turn to say goodbye. He shook her hand, "I just want you to know that he didn't spend all of the time you were unconscious out on holidays. He sat in that room for days on end, making sure you didn't destabilise."
Fenn pulled him into a tight hug, "Thanks, Ianto. I really appreciate that." She drew him out to arms' length, smirking slightly at the look on his face; but then she lost all trace of humour, "and look after yourself, won't you? Don't let Jack ignore you, Ianto."
Ianto was about to answer when the train came around the corner with a noisy screech that drowned out his words. Fenn smiled at them, and moved to find a carriage. Just before she got on, Jack yelled out to her, "He's coming back, Fenn!"
Fenn called back, "I know!"
Ianto yelled, "How do you know for sure?"
She grinned cheekily as she waved and replied, "He never told me goodbye!"