You ended up with an attached little brother ever since your parents died. It wasn't supposed to be like this, of course. Your brother was adopted, having you also in mind, thinking that you and him would grow up normally with them supporting you. But that all came crashing down when they died. Now, you've raised your little brother, and yet he still hasn't grown up. Because ever since mom and dad's death, you were his only family left, and friend, in a way. And he's been super dependent on you since then.

So now here he is, scared of a spider he saw in his bedroom.

"THERES A SPIDER!" He yelps, then comes running to you, hugging you.