I love you like a brother (bl)

To get your oniichan to love you= Tie him down + reaffirm him that he is yours if he runs away just kidnap him and keep him in a soundproof room

Chapter 3, best friend story with him and his stepbrother

Psychotic younger brother that will use any means to grab his bros love, even by stealing his lovers but fails in the end

The younger bro seems to have feelings for the older we will see