The Moon
The Moon. Being named after a star gave the boy admiration for it when his hired teacher taught him Astronomy. Now after only one year in Hogwarts he hates it. Once a month it took his best bud away from him. Once a month it steals that same boy's sanity. Once a month it turns him into a monster who hurts not only himself, but also his friends, namely one. If Sirius had the power and will to, he'd stare at the Sun forcing it to go back up. When that didn't work, he'd stare at the Moon trying to force it to go back down. As it was, that failed as well, leaving two torn boys to help each other after the fight that had happened under the moonlight.