I've embedded the links in the story titles or in the part number, so just click on those and you should go straight to the fic.
First up have to be my favourites from
Miles To Go Before We Sleep [PG-13] (1 Part) and
Promises To Keep [PG-13] - Part 1 Part 2
Next comes Forever For You - An Alternate Tale Of The 456 by
Then there's When Everything Changed [PG] (20 Parts) by
Finally, Lazarus [Mostly PG] (31 Parts) by
Hope you enjoy. If I get any more suggestions, I'll add them to the post.
Updating 14/2/13
Here are a few more suggested by my lovely friends!
Throughout Time And Space [NC-17] (25 Parts) by
Chosen [PG-13] by
The Rose Of Jericho [M] (5 Chapters) by
Once Lost [M] (6 Chapters) by Jax25
The Jacks [T] (30 Chapters) by Tylluan
Do Not Stand At My Grave And Weep [M] (5 Chapters) by black.k.kat
Promises [M] by Gryvon
The Archivist [U] by
Get Your Bearings [NC-17] by
How Ianto Jones Saved The Future [A] by Chocolatephysicist
Ghost Story [T+] by