My Life for His

It began when Sherlock was eight, and he attempted to climb all the way up to the highest branch in the old willow tree in his back garden.

He'd thought he was still small enough that it could support him, but the second he'd grabbed hold of it to pull himself up, the branch snapped, and down he went, plummeting a solid twenty metres.

The odd thing was, he never actually hit the ground. Johnlock Guardian/Protector AU.