A/N: Thanks to karaokegal or a little look over this snippet. And whoa, this is probably the shortest fic (or ficlet?) I've ever written and probably the closest I'll ever come to writing a drabble anyway.
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Guilt
She was there, in his dream - which was unusual enough for someone who barely slept at all - and he knew that he was dreaming, but still... so real.
Gwen!
He could feel the warmth of her skin when he touched her, smell a trace of her perfume when he hugged her and taste her after he kissed her, desperately, despairingly, trying to hold her... because he already knew what would happen.
"I have to go, Jack."
"You can't just go!" His voice sounded disconcertingly pleading, an echo of her voice in his mind.
Gwen shook her head, a tiny, sad smile on her lips. "I can. Just watch me."
With that she was gone and...
...Jack Harkness jolted awake, cold sweat on his forehead, his heart not just racing but also terribly aching. With a sigh he let his head drop back to rest on the pillow before taking a deep breath, trying to shake off the lingering feeling of guilt and loss and hurt; to no avail.
Sometimes he wished he really wouldn't need to sleep at all, because even if he only slept once in a while his dreams were painful enough.
The dreams of Tosh and Owen had lost their terror and even the haunting images of Ianto and Steven (and Alice for that matter) had stopped torturing him in his dreams after enough time had passed.
But Gwen? Gwen still continued to trouble him on the rare occasion that he slept, teasing him, taunting him... abandoning him like he abandoned her, breaking his heart every time anew.
Obviously he had overcome the loss of those loved ones that he failed, but not of those he left behind.