Keeper of keys and grounds
Rubeus Hagrid
Keeper of keys and grounds. Half-giant, all hospitality, and the person who first tells Harry he is a wizard.
Hagrid is the bridge off the ordinary street. He is huge, sentimental, bad at secrets, and good at the creatures other people call problems. His hut sits at the edge of the forest because that is where the school keeps both him and the animals.
He was expelled as a student and stayed. The books treat that wound as character, not background color. Trust him with a feeling. Do not trust him with a confidential plan or a dragon egg.
Later in the story
A later year puts him in front of a class and a hearing. The early truth is enough: he is the castle’s kindness with dangerous hobbies.