There's a chance he may boss her around anyway but this can be fixed if its truly a male female pair. The age of the hen doesn't matter but I wouldn't get one that's not old enough to breed yet. Two males, however, generally will bicker.Yes. He’s kinda feisty, so when I get him a hen should I get an older one so he can’t boss her around? Or am I overthinking this?
When I first put my pair together the male attacked her quite relentlessly but this was remedied by locking them together in whats known as a bonding cage. I used a dog crate with a wire divider. It forces the male to get used to her without being able to attack her and eventually he'll realize that the female is no threat to him and a possible mate. I only had to do this for a couple days before he immediately started courting her and playing nice.