@RamenRider
I agree with you that they none can be saved in Slow Life but have to disagree on the brother being more "malevolent".
Taking in consideration the sister has max status in everything and what he does are suposed to be punishments for her missbehaviour, with maybe also being training so she learns to control her power since having that much power while being a child can be really dangerous for everyone involved, and your requirement of "put him through anything that she isn't also capable of dealing with" the brother comes out as less abusive than the sister.
As you said, and I agreed, everyone in that story are garbage people that abuse the MC at all chances but that doesn't matter since the problem is the people defending the sister in the coment section there while condemming the brother here. The sister is worse as, so far, most of the abuse from her is underserving while here it seens to be an attempt to have her behave as a noble lady.
I have to say, because someone will try to say I'm defending the brother, that his actions are still too extreme and, from an outside perspective, wrong.