Hmmm

I hope they'll have that normal sibling relationship where they act like kid but care about each other

Yeah, but then again his indifference to everything she suffered through… I’m not so sure he deserves that chance

He didn't know he had a sister with 'his mother'

Plus he also felt lonely since his half big brother didnt acknowledge him due of his evil mother

I went back to the first chapters, it doesn’t show whether he saw her being abused or no, so I guess for me it all comes down to his role in it. If he didn’t know he had a sister, but was a bystander in someone’s abuse then he doesn’t deserve it. If he never even knew that she was being neglected then I guess you’re right, he deserves a chance. Tbh I would love to see the perfect son turn on his mother, wonder how she would react.

he's a kid

I mean in her past life, he wasn’t a kid anymore then

well spoiler said he didn't know anything about her especially that she's his "biological" sister. i dont remember properly but i think he reflects on not treating her properly (i could be wrong tho )

I guess we will see. I reread the beginning and there was nothing said about their relationship, so maybe we will get to know more in the future