Time Turner was at it again, trying desperately to repair the TARDIS he'd come to call his greatest friend. She'd been hanging on to life for years, but the ship was losing her grasp, and Time Turner feared that the day he'd officially be trapped in Equestria was dawning. The ship's chameleon circuit had allowed her to take the form of a blimp - worn by time. It looked particularly small for what it was, and that fact was putting far too much strain on the TARDIS' compounds for how weak she was. Worse, she was an old enough model to still possess consciousness.
The cardboard brown pony dashed madly about, trying desperately to figure out how to get the old girl to work. "Come on, pal, you can get us out of here. I know you've got the heart." Flipping a panel underneath the blimp's control panel, he squeezed into the space that opened up to a staircase.
It was right then that he heard the door to his home open and the sound of hoofsteps echoing down the corridor. "I don't have time for this."
Trotting back up the stairs and poking his head out of the TARDIS, he spotted Derpy.
"Hey, Doc, I know you're probably busy, but I was wondering if... well... you could help me?"
The Time Lord was very unimpressed. "The TARDIS is dying. I don't have time to..." A wheezing, alien sigh caught his attention below him, and he immediately ducked his head back into the TARDIS without further word.
"Do you need me to get Twilight? She might be able to help with magic."
The other pony didn't hear. It was too late... the TARDIS was dead, and there was no bringing her back. Time Turner hung his head in sorrow, but no tears were shed.
...he'd long ran out of tears for the lost.
Laying down besides the dead console, he let himself give up.
It was said that a TARDIS would die without a Time Lord.
The Doctor could not live without his TARDIS.