From Azkaban to Hogwarts

There are five Hogwarts houses in total. This is common sense.
So it’s not surprising that you start in Azkaban, right?
——Soon
after William opened his eyes, he found himself in Azkaban.
Shortly after an inmate named Mundungus was released from prison,
strange things happened.
A unique job fair was suddenly held.
“What, Hogwarts is recruiting professors?”
“Coming to Azkaban?”
“Professor of Defense Against the Dark Arts?”