Mrs. Norris wasn't a particularly old cat, but she had seen things other cats didn't even dream of.
She had seen the age of the Marauders, the lively kids, which were now either dead or treated like dirt, in their prime. She had seen the love that had blossomed in these halls, and she had seen the rat, stag, dog, and wolf many a full moons, roaming the village.
She had seen ages darker than the darkest night, and seen healthy people at one point, not knowing it would be the last time her feline eyes laid sight on them again. She had seen death and fear; knew it intimately, and wished she didn't.
She had been disliked, hated even. But she had seen things. Things that not many wizards had. Things that no wizard wanted to witness. But Mrs. Norris had still seen them.
She had seen an eleven-year-old boy, determined to keep Voldemort away, for just one more year. One more year. She had seen the reflection of a very large green snake with horrible yellow eyes, and later found out that that same boy had slayed it. She had seen her worst memories over and over and over again, only to be stopped at a later date by a thirteen-year-old boy who only wanted his godfather safe. Mrs. Norris had seen the trials and tasks that no fourteen-year-old should go through, let alone tasks that were meant for seventeen-year-olds!
She knew dark times lied ahead. She knew. But with that knowledge did not come fear, because as she witnessed another year of the same boy's life, and his hardships, she knew that whether she came out of this alive did not matter. Perhaps she could die by clawing old snakeface's red eyes out. She had seen countless horrible things. Too many. And yet she still saw another year of Harry Potter's life. But she also saw the end of a great wizard. And as she saw one of the only people that did not dislike her run out of the gates of Hogwarts, she knew that the darkness had only begun.