Daniel has waited for her thousands of years and he will wait thousands more, as long as he knows one day they will be together. (Some spoilers for Passion)
He had never loved anyone the way he loved Alex Reid. But that's exactly why he had to let her go. (Set in the last few minutes of 2X11 En Bloc)
How could he explain to Joan and Martha that the reason he could never loved them was that the Time Lord's love lasts forever, and there was only one woman in his mind? (Post 3X09, "The Family of Blood")
Post season 2 finale, "Broken Hearts". While Alex is in surgery, Charlie tries to find a way for "sane" and "ghosts seer" to work out.
As the Doctor realized it was Trenzalore he was standing on, hew felt relieved. For the first time in his life, he knew his pain was finally about to end. [Set in "The Time of the Doctor"]
After Wilson's death, House makes the one decision he's able to make. But first, he knows he must see someone he hasn't seen in a long time. (Post "Everybody Dies", obviously)
Sequel to One Last Goodbye. John sets out to find Elizabeth and help her restore her memory. Post series finale, "Enemy At The Gate".
Despite saving so many people, including his own race, the Doctor still has his doubts about him being a good man. A sort of an alternative ending scene for The Time of the Doctor.
The Family discovered just how merciless the Doctor could be at times. But at the same time, they also discovered how kind he could be - and how fast he could lose that side of him. [Set in the end of "The Family of Blood", spoilers for "The Day of the Doctor" and 4X13 "Journey's End"]
John could never tell Elizabeth just how much he cares for her, but after rescuing her from Kolya's hands, he doesn't have much of a choice but to show her. [In the end of & post 1X11 "The Eye"]
The experience Elizabeth had just been through is horrible, but she's not the only one. More worried than ever, John watches over her and tries his best to help the most important woman in his life. [Post 3X06 "The Real World"]
Sarah wakes up in the infirmary in the end of Chimera (7X15) to find Daniel waiting for her. Short one-shot on the day after.
What would have happened had Daniel managed to help Jack ascend back then in "Abyss"? Would Jack really have followed Daniel to philosophy... or would he have more... fun plans? [AU from 6X06]