After i saw The Doctor Whooves episodes, i wanted to continue that. So the Daleks found a way in to ponyville, the doctor came back and with Derpy they defeated all the Daleks. But, there was paradox, the doctor was never supposed to be there, so him and his TARDIS ell through the rift, leading them separated. This is what Ditzy does, I hope you like!:
(I don't think it's done, nor ready to be posted. I have to do some major edits. XD) Here is Derpy jumping through a time rift to reach The doctor. It all starts in ponyville after the battle against the Daleks:
As she jumps in and watches the rift close with Rainbow Dash, she smiles and looks forwards at the light, happy that she'll be able to see that Doctor again.
I think this could lead on to an entire new series on derpy being the doctors companion right after Rose and before Martha Jones! ^_^ (don't steal!)