I have two beautiful Cockatiels, a female lutino named Polly and a male regular gray named Paul.

I have a very strong bond with Polly and she gives me kisses on the nose. I love her so much.

On the other hand, Paul is the DEVIL. I don't think I'll ever be able to hand train him. When I reach into the cage, I be sure I do it slowly and with a confident smile on my face. But when I reach in to pet him, he won't let me get within 5 inches from his head before he flips out, screams, hisses, spreads his wings, and tries multiple times to bite my finger off. I tried to train him, but he is just plain untrainable. Seriously, I've NEVER touched him b4. NEVER. He ripped out a chunk of my flesh the other day.

He is also aggressive towards Polly.

He won't even let her sit on the same perch as him without biting her in the neck.

I don't know why he's doing this, because there is no reason to.

His environment is perfect. His cage is always clean, I give them fresh water every hour, and I always feed them fruits and vegetables along with their seeds. I give them millet spray, too.
I always try to get them outside their cage, but I usually leave Paul in the cage because whenever he does come out he is very stubborn to go back in. He isn't hand trained, and when I try to grab him from behind (My only choice at this point,) he bites me, struggles, and when I release him he flies onto the top of the doorway to escape. Yesterday, I had to get a hand towel and sneak up behind him, grab him with the towel and put the towel in the cage just to get him back inside.

So, why is he so aggressive? I make sure their environment is perfect and am always super nice to them. They're my little angels. I just want Paul to trust me, stop all this biting, and let me hold him.

BTW, treats do NOT motivate him. I've tried bananas, sunflower seeds, Peanut butter on toast, EV.ERY.THING. Nothing works with him, NOTHING!!!

I probably have the most aggressive cockatiel in captivity!!!