Charmed Life  - Diana Wynne Jones
Eric, also goes by the nickname of Cat, and his sister, Gwendolen, were orphaned after their parents died in a boat accident. Both are sent to live at Chrestomanci Castle after Gwendolen sends a letter begging the current Chrestomanci -- who is a distant relative -- to take them in. Cat just goes along with it. He always follows his sister. Especially now that their parents are gone. But, trouble starts when they move to Chrestomanci Castle. Gwendolen is mad because the Chrestomanci refuses to recognize her magical talents and does all sort of things to try and get him to notice. When that doesn't work, Gwendolen makes up a plan that will make everything go her way. When Cat is left behind by his sister that's when the truth is revealed to him.Cat was very easily controlled by his sister and it really made you a bit mad that he let her to so much stuff, but in my opinion, Cat is still a very likable character. Gwendolen was a very good villain, that's for sure! She was so mean to Cat. Chrestomanci was very mysterious at first and overall he is an awesome character. I love the world Diana Wynne Jones created in this book and the idea of other worlds. DWJ's books are so amazing and unique, Charmed Life was no different.