This happens at the end of torchwoods children of earth just before Jack H. says goodbye to Gwen and Rhys.
Explaining the painful
Jack was staring down at the road at the bottom of the hill waiting for Gwen and Rhys to come breathlessly round the corner, He'd specifically chosen this hill for that very reason to watch them lug themselves up the hill. He was hoping just hoping they'd take out some of their anger at him for this out on him.
He was looking at the clear night sky, thinking of how he was going to hitch a ride and where he was going to go when a wind picked up, he ignored it until he heard the ancient wheezing and groaning engines of his favourite time capsule dematerialising into being. But for once he didn't run to the Doctor like the love sick puppy he was, he just looked at the police box long enough to determine that she was bluer than he'd ever seen her and that she had some sort logo on her left door, before lifting his gaze back up to the stars that seemed to twinkle in his pain, too pretty for his feelings right now.
"Beautiful aren't they? Though when you're as old as us they seem to dim and become boring, I'm guessing that's how you feel, eh?" said a voice he knew wasn't the Doctors but right now he didn't care so he said,
"yeah when you put it that way…" a pause "Doctor what are you doing here?" that's when he looked at the Doctor, he was young much younger than he would have thought possible for the Doctor, but he sort of suited it. And for a guy who hates military he sure can pull of a military coat, he looked as good as he did in the brown trench coats now in that green navel coat, though the bowtie was debatable. His hair was a little unkempt as if he'd been living in a cell for a while and his fringe of floppy hair drooped down into his eyes. He looked the image of youth, except the eyes. The eyes that showed him to be an old man who'd seen and done many things, some of which he's not proud of, his eyes were clouded with heavy guilt as if it was a recent development he hadn't quite accepted yet. Jack saw all of this in the split second he caught eyes with the Doctor.
"To put it loosely I met a guy in a bar, who told me too look up the 456, and I'm sorry Jack, but it wasn't your fault and if I was stuck with the same situation I would have done what you did. In fact I have in the past, Dorothy McShane is a good example of this, oh I loved Ace, still do, but the point is with situations like this you have to look at the bigger picture." He cut of and looked at Jack with eyes that had seen too much and right now Jack felt like was the same as the Doctor the man he had aspired to be like since the Doctor had told him that he had caused the gas mask Zombies or rather when he was saved by him as he'd thought he was going to die before that. He had always known the Doctor has had to make hard decisions but ultimately he does the right thing and now Jack could see the Doctor inside of him-self. The Doctor wasn't going to stop him from mourning or leaving he was genuinely trying to help him feel better.
"Why didn't you come?" Jack asked suddenly looking the young Doctor in the face, which had darkened considerably and he sighed before answering,
"I'd hoped you wouldn't ask that, but to put it straight, I found out after it had happened, from a brilliant source may I say, that I wasn't there and wibbly wobbly timey wimey, I couldn't go there and help because I wasn't there in order for me to be there, Time you can't keep it straight in your head," he finished with a slight frown "it was a…" he cut of thinking "a self-full filling prophecy, if you know what I mean."
Jack mulled this over and said "Okay, I guess that makes sense," he sighed and continued "you'd better go, Gwen an Rhys will be here soon." He knew he was pushing him away at the moment and he knew that the Doctor knew. Jack expected the Doctor to protest but he just stepped closer to Jack and pulled him into a tight embrace which he leant into and whispered "you'll see me again soon, the earlier when i… well let's just say you were one of the last people I saw before I last regenerated, and by the way find out the rumours of me and River Song, eh" he then did something that surprised Jack even more, he stepped back and gave a long deep kiss on the lips, similar to the one he gave the Doctor on the game station but the Doctors portrayed reassurance and a promise of hope, before stepping back, one look at Jacks face made him chuckle and say "What? My kissing skills aren't that bad" he winked and walked back to the TARDIS and Turned round with pursed lips nodded once and disappeared into the glow of the TARDIS interior and withit disappeared into time and space.
Jack didn't know how to feelhe was exstatic because the Doctor kissed him properly, gut wrenching guilt, he had pain from all of his loses but a little bit of hope from what the Doctor had just said, I fact he wouldn't be surprised if he were the stranger in the bar the Doctor talked to, he smiled in anticipation and then as he heard Gwen shouting for him his face morphed into sadness along with his feelings maybe it wasn't such a good idea to make them mad at him.