(Book one of the I Will Do What I Must series) Obi-Wan has been through it all; now he's able to add killed by your apprentice to the list. To an average person, getting to go back and try everything again would be the best news in the world. But Obi-Wan is not an average person; he's a person whose whole family was slaughtered and a man whose closest friends turned against him.
A myth has been passed for centuries down the Hogwarts students and professors. Here we see how is it that the Ravens myth came to be. One small Ravenclaws friendship with two feathered friends came to be his rescue.