Jack had become accustomed to dying and then waking up alone. He was alone; the only one of his kind. No one else suffered from the curse he had. No one else could die and survive. It didn't matter what the circumstances were; he always woke up alone, either surrounded by the dead or abandoned by the living.
That all changed the moment he met Ianto Jones. To begin with, he was just a new recruit who made the coffee and looked good in a suit. And then Jack began to take a closer look at him. It was interesting, the things he found out. Not that there was much. Jones kept himself to himself most of the time. They had gotten together, after the Lisa incident. Ianto seemed to forgive him for that.
Jack still died, on occasion; the events with Abbadon, for example. But this time, when he woke up, he had something to return to. Someone to share things with. He was no longer alone.
Until that fatal day at Thames House.
A deep inhalation of air was his first action. He blinked, and sat up. The red cloth wrapped around him pooled to his waist, and he turned to his left quickly. Ianto lay next to him, cheeks drained of their usual colour. Jack turned away again.
After regaining his composure, he moved so he was holding onto Gwen, looking at Ianto. The loss, guilt, grief and pain hit him simultaneously, and he could not stop his eyes from welling up with tears. He realised that his kiss had not worked, he had failed to save another person. Now he would have to wake up alone again.