Five Times the Doctor Made It Better, Just a Little Bit, by
lightgetsin.
PG-13. Gen.
“You’re going to help me?” Jack asked.
“Sure,” said the Doctor. “It’s on my to do list - just put it there. Right after refitting the horologous flux control nexus and preventing that twenty-second century American idiot from spreading marshmallow peeps across the galaxy in the first human Diaspora.”
Spoilers: through Torchwood
What the title says: moments between Nine and Jack, Ten and Jackie, Ten and Rose, Ten and TARDIS, Ten and Jack. Every scene resonates, and the last is the stuff squees are made of.