Mentor. A Tour official who will be at your service until halfway through the Tour, at which point you will unaccountably lose him. ... He will reappear, smugger and bossier than ever, near the end of the Tour, just when you thought you were doing rather well on your own.
"The mentor figure dying is all part of the hero's journey, my dear."
— Gordon Edgeley, Skulduggery Pleasant
He could not let anybody else stand between him and Voldemort; he must abandon forever the illusion he ought to have lost at the age of one, that the shelter of a parent’s arms meant that nothing could hurt him. There was no waking from his nightmare, no comforting whisper in the dark that he was safe really, that it was all in his imagination; the last and greatest of his protectors had died, and he was more alone than he had ever been before.
"Harry... you must realize that if you choose this man as your teacher and your friend, your first mentor, then one way or another you will lose him, and the manner in which you lose him may or may not allow you to ever get him back."
— Dumbledore, Harry Potter and the Methods of Rationality, chapter 20