Hi,
Not all birds are interested in being pets. Sometimes you get a cockatiel, male or female, that is simply aggressive and nothing works as far as trying to tame it. Hormones certainly play a part, even with two males together. They may not be super bonded, but the aggressive male may like the other more than you think. This is the age when their hormones really peak for the first time, so he may settle down after a few weeks or even months. Males like this often are even aggressive with their mate, so he’s not necessarily cut out to be a breeder. He might be friendlier out of sight of his cage. Be patient with him, but understand that this just may be his personality and he might not change.
Thank you for asking Lafeber,
Brenda