SPOILERS FROM HEAVEN SENT

:skull: :skull: :skull: :skull: :skull: :skull: :skull: :skull: :skull: :skull: :skull:

:maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf: :maple_leaf:

:warning: :warning: :warning: :warning: :warning: :warning: :warning: :warning: :warning: :warning: :warning:

"If you think because she is dead, I am weak, you understand very little. If you had any part in killing her, and you are not afraid, then you understand nothing at all. So for your sake, understand this -- I am the Doctor, and I'm coming to find you. And I will never, ever stop."

And he never stopped.

Tormented by the fresh death of his best friend and the constant torture and fear of forever being alone for billions (seriously think about that....Billions) of years and he never stopped.

It took him billions of years and even more deaths as he punched over 20 ft of material stronger than diamond with his BARE fists, enduring both physical and internal pain... but he didn't stop.

Why?

Because clara still made him strong.

Clara in his head, depicted just like she was when alive, gave doctor a harsh but loving pep talk that kept him going for billions of years a lifetimes of death.

He kept his promise.

He didnt stop.

One thing im wondering. Why didnt he regenerate? He had enought time to... He was given a new regeneration cycle...