Hormones, my friend.
I have one roo who is a jerk (he's tiny - weighs just 1 lb - my 8 week old pullets are larger), so he can't hurt anyone. And I have one big boy who is more respectful of me. I raised them very differently because I didn't want the big boy to turn out like the tiny jerk.
The tiny guy was supposed to be a pullet, but you know how that goes. I cuddled him because he was so cute and tiny. He was a total lap chicken. As soon as his hormones started raging, he turned on me. He clearly doesn't respect me and sees me as an intruder and a threat. He has gotten a little better over the years, but he is definitely not a nice rooster to me. He's GREAT with my girls, though.
Here he is next to a 6 week old chick - lol! His name is Picotee, and he's gorgeous.
Fast forward a few years. I ended up with another sexed pullet who turned out to be male. As soon as I knew he was a cockerel, I was hands off with him. I treated him like livestock instead of a pet. He now gives me a wide berth whenever I'm in the coop or run, which is a very good thing because as large as he is, he could do some damage were he to attack anyone.
Here's the big guy. His name is Cayenne.
I can't say that treating the big guy differently has helped, but it certainly hasn't hurt. It's something I learned from seasoned rooster owners here on BYC, and it's worth considering if you treat your cockerel as a pet and he is starting to show aggression towards you.
However, some roosters are just jerks, unfortunately.