After the tragedy that unfolded when he developed his quirk, he made a promise to keep you from harm. He had nothing left except you, his younger sibling; he adored you with every fiber of his being

Despite being the younger sibling of a major villain, you remained blissfully unaware of his heinous actions—to you, he was your loving big brother whom you’d bicker with every now and then.

He kept his villainy a secret from you… well, until you caught a glimpse of it from the news.