Thank you for your reading and sending this message. This took me some time to think of. 

So,

There are certain parts that might change, but I don’t think he’d be too far from where he is now. I think he might’ve even turned out to be a mean unlikable person, or maybe fell into non-familial abusive relationships. It could go to both extremes honestly.
His issue isn’t only in the beating, after all. That was coming from one side. 

I wonder if there would’ve been a relationship with White at all if Black wasn’t abused. Taking you back to chapter 9, White only found the courage to approach Black when he started to see the bruises and the change in him. That’s regarding their relationship. 

As for Black himself and how the beating isn’t his only problem;

(spoilers under the cut for those who didn’t read chapter 32)

As shown in the chapter, Black is a spoiled kid who doesn’t take no for an answer and is getting things the way he wants by nagging and screaming. His mother and older sister made his wishes their commands, and if they can’t meet them, they always had something to offer so Black would forget about what he wants. (new tricycle so he’d drop going to the park)

They loved and spoiled him without actually raising him up. And above all that, they were overprotective too. He can’t go on his own and had to be walked everywhere. More on this will show up with time.

Funny how they were trying to protect him from all harm outside, when it’s inside that’s hurting him.