Tenth Doctor (2)

Do I Dare To Eat A Peach? (Doctor Who) by Rivendellrose
The Doctor's getting older, and not all his former companions are all that broken up about not staying with him forever. And that's not a bad thing.
Listen (Doctor Who/Buffy) by Evilawyer
The pixies say you save worlds, too, but that sometimes salvation and destruction wear the same gloves.
SA: Superheroes Anonymous (Doctor Who/Multiverse) by Pitry
The Doctor goes to a support group.
To Be Left Behind (Doctor Who/Narnia) by WingedFlight
Susan knew what it was like to be the only one left when all others had perished; she knew how it was to be older on the inside than the outside; she knew how it felt to be so alone. Maybe she wasn't so different from the Doctor after all.

Countess and the Doctor

(1) Right At Home (Vorkosiverse/Doctor Who) by Sahiya
"Doctor, this is my son, Count Miles Vorkosigan. Miles, this is the Doctor. Please try not to blow anything up, either of you, while I go pack a bag."
(2) A Skewed Perspective (Vorkosiverse/Doctor Who) by Sahiya
"Doctor. Do you think it's possible - just possible - that your semi-immortality may have given you a skewed perspective on the subject?"
(3) Only Biography (Vorkosiverse/Doctor Who) by Sahiya
Biographies were the Doctor's favorite literary form.

(1) Interlibrary Loan (Doctor Who/Discworld) by Dame Ruth
A short piece of mildly silly Discworld/DW crossover crack.
(2) Bananas (Doctor Who/Discworld) by Dame Ruth
Another crossover with the Discworld. Sometimes a banana isn't just a banana -- sometimes it's a daiquiri.
(3) Cupid's Labyrinth (Doctor Who/Discworld) by Dame Ruth
The last story in the L-Space Trilogy. The Discworld crossover continues; sequel to "Interlibrary Loan" and "Bananas".

(1) Now We Have a Map of the Stars (Doctor Who) by Zauberer Sirin
Total AU: Martha never left and the Master was never killed. The Doctor keeps his promise of taking care of him. Sort of. Martha helps. Kind of. And then Dalek plot happens.