This author is a bit poisonous, so be mentally prepared for the trap.
The story of the parent generation, because I want to write all the CPs at once, so I won't go into the timeline. The main CP is Professor Godfather SSSB, and the other CPs are a bit too much.
If you want a more useful copy, it would be - Sirius spent some time with his childhood professor in the form of Animagus due to an accident.