Red John is an egoistic son of a gun. Look i love the guy with all my heart, but the way he says "Who are you? Huh? No one" I'm probably not 100% right on this, but this is from my observations and since i'm trying to become a psychologist.
But i think Thomas had a problem, he thought that he was someone that no one could beat. Like his father did when he beat up his mother and him as a child. You see my point? If not...

What i'm trying to say is: Red John had daddy issues.

It might sound weird but think about it. How Thomas said "Who are you to judge? Who are you?" and patrick replied "I'm no one..."

He wanted to beat his father, make him feel like he isn't great.
Basically what i'm trying to say is Red John had problems, He had Daddy issues and tried to be someone greater than his father but at the same time a bad man...
Also the ornithophobia (fear of birds) could be something from his childhood. Who knows?

Now i'm not saying this is Plausible and I'm not saying that this is unlikely either. But this is from my observation.

ALSO SORRY FOR THE BAD ENGLISH I'M FROM SWEDEN xD sorry :/