I’ve been hiding in that song for decades. And now I’m going to burst out of it. Hold tight! No. But. Sorry. Have you got the rights to that song? I created that song.
Doctor Who: The Giggle (Target Collection) by James Goss
The way Donna rushes to hug the Doctor after coming back from the world where they never knew each other and the Doctor was dead.
The way the Doctor is so pleasantly surprised by this unexpected display of affection, and he is so happy to have this hug, they are both so happy to be reunited, and they don't even know here that they are about to lose each other for long ages.