The friendship between the three was solidified when, on Hallowe'en in 1991, the three were forced to confront a mountain troll. Unaware that a troll was on the loose in the school, Hermione had spent that day crying in the girls' bathroom after overhearing Ron making unkind comments about her. The troll made its way into the bathroom she was in, and Harry and Ron came to her rescue, saving her. When Professors Minerva McGonagall, Severus Snape, and Quirinus Quirrell arrived at the scene, Hermione covered for the boys, claiming she was fighting the troll because she had thought that she could fight one, having read a great deal about them, and that Ron and Harry had merely come to help her escape. From that point on, the three students were best friends.