Was the Phantom from Phantom of the Opera born deformed or did he become deformed?
Erik, the Phantom, was born deformed. Leroux uses this information to demonstrate that even from birth and childhood, Erik had to fight for his place in society and acceptance. His own mother encourages him to wear a mask, and he becomes part of a "freak show" of sorts as a child.
Leroux's phantom is very similar to Mary Shelley's monster in Frankenstein. They both are physically unacceptable to society and after experiencing humans' repulsion and abandonment, they begin to exact revenge upon the human race. Interestingly enough, both men see women, or a female companion, as the solution to their problems.
I, like you, favor the phantom over most of the novel's other characters. The Persian is also a very interesting character who, for some reason, is cut from the film and musical versions of the novel.