It throbbed behind his forehead protector. It had been put into his eye socket in its sharingan state and he never, for all his genius, learned how to turn it off.
Oh, he had developed it into its complete state, even figured out how to acquire the mangekyo sharingan without paying that unacceptable price. And yet the act that ought to have been the simplest eluded him.
Sometimes though, Kakashi didn't mind so much. Sometimes this grinding on his patience, this ache, reminded him of Obito so vividly that it felt like the boy he had once known was still alive.