"Empty Tombs" by DaraOakwise
"There was another way," he soothed. "I went back and hid it in a pocket universe. Ended the Time War, just the same, without me committing fratricidal genocide. It looked like death, but it wasn't, like what we did at Lake Silencio."
River pressed a palm to her forehead. "That's a completely different example, and you know it," she gasped. "The destruction of Gallifrey is a fixed anchor of the universe. The Big Bang, the End of Time, the Destruction of Gallifrey. Setting aside that you broke through the biggest time lock ever created, you also undid a fixed anchor of the universe!? Without destroying said universe? How?"
"I had thirteen versions of the Tardis, two millennia of calculations, one conscious superweapon, and 26 hands," he shrugged, his head still in her lap. "I wrapped them all around the universe and asked it to be still."
"You asked it to be still?" she asked incredulously. "And the universe listened? Does that happen a lot now?"
"Hardly ever," he said, gesturing ruefully to his still-healing body. "
That's ... possibly the most terrifying thing I've ever heard. What do the Time Lords think of you commanding the laws of time to your will?"
He frowned. "I didn't command them to my will. I asked them, nicely, with mathematics, if they wouldn't mind redefining themselves. Slightly. Why are you looking at me like that?"