10 months is about the age they become more protective in my experience. He will still go through some more changes. If you are going to keep him consider post #18 and #25 in the following thread link. Very helpful.I have a 10 month old Barred Rock Roo from a McMurry Hatchery and he in the last month has become very aggressive. I have to do work in the run before I let him and his 7 hens out in the mornings and I have to lock him out of the hen house to do work and gather eggs inside the hen house because he will attack. I didn't want a Barred Rock Rooster but I knew that's what he was the day I received them from the Hatchery. Ever who sexed my order should have knew that chick was a rooster.
https://www.backyardchickens.com/t/1149551/aggressive-rooster/10
But if you do not need or want a cockerel, life is too short... let him go. Even if it happens to be to feed some one else's family if you aren't able to do the deed yourself. There is no shame in that and many of us do it very humanely with the bird nice and calm.
It's unfortunate that the hatchery 90% policy doesn't account for the time, energy, or emotion it takes to deal with getting an unexpected cockerel.
Best wishes, whatever you decide!
