What are Gally’s thoughts about Thomas and why he was sent to the Glade?

Gally has vague memories of Thomas from the memories that he regained during the changing. The fragments of memories do not appear to be good so Gally spends his time sulking and giving Thomas the "evil eye". Gally hates Thomas and is a clear antagonist to anything that Thomas stands for or tries to accomplish. He spends his time trying to intimidate Thomas by making empty threats to him.