Crookshanks
Disclaimer: I don't own Harry Potter, and all rights belong to J. K. Rowling.
A gentle swish of his tail flattened the grass around him, and laid down on the grass, taking in the star-filled sky above. He closed his eyes, and pondered upon the circumstances that had led to this.
Right now, he knew, Harry Potter was sleeping, thinking that he was safe.
How very wrong he was.
But then again, how were all of those fools supposed to know, that he, Lord Voldemort, was still alive? Even he had not known, about this. The Potters were no longer alive, to realize that the cat they had kept in their house, was he. The day he attempted to kill the boy, a part of his soul latched on not only to the boy, but also to their cat.
He remembered, wandering around, testing this new body. He finally wound up in a pet shop, in Diagon Alley, where he could keep his eyes out for news. He decided that this body was to be his safeguard, he would not reveal that it was his eighth horcrux.
Then, one fateful day, the Potter boy and his friends wandered into the shop. He seized the chance, became friendly with the mudblood, and kept an eye on his enemy.
How curious, he recognized the rat at once. It was the traitor, Pettigrew. He tried to punish the traitor, again and again. Then, at the school he became allies with the large dog, Sirius Black.
Even that man had realized that Crookshanks was smart beyond normal cats, but he never suspected.
However, now was time to stop dwelling on previous memories. Harry Potter could no longer sense his presence, and he would be unprepared for when he would rise again.