In which the Doctor is confused while Rose is optimistic

So what happens to 10.5 after 10 left with Donna in the TARDIS?

A/N: This is a repost from my FanFiction *dot* net account. This is from 2012 so my writing has changed, I think, but I'm still really proud of this one! Also, it was the first time I ever wrote a fanfic for any fandom so... enjoy! And tell me what you think, I love getting feedback!