Comment by Kudo on Can a Lover Also Be a Substitute? - Chapter 10

For those who seemed confused about the characters I'll explain, this particular manga is about two sets of twins, we have the first set who were born into a rich Chabeol family, and clearly they don't get along with each other at all they both have black hair the only way you can tell them apart is how their hair is styled, the second set of twins have blonde hair and blue eyes which is somewhat pretty rare in this manga's  universe, The youngest twin of the blondes, asks his older brother help with relationship advice and the older brother in that dating the youngest(oldest blonde dating youngest brunette because younger blonde asked him to).

and now clearly we are going to see that the oldest of the brunette twins is going to end up being with the youngest of the blonde twins.

I try to simplify it and make it less confusing