A yandere girl in manhwa is often extremely possessive and obsessive about the person she likes. She can go to extreme lengths to keep them close, sometimes even resorting to violence or manipulation.
In manhwa, yandere boys typically have a dual personality. They might seem normal on the surface but go to great lengths to keep the object of their affection close. Their actions can range from overly protective to outright violent when they feel threatened.
Well, it's not really about age. It's more about the characters' feelings and circumstances. Some manhwas might challenge the idea of age and focus on true emotions instead.
In yandere x reader fanfics, yanderes usually display intense emotions. Their love for the reader is not the normal kind; it's more of an obsessive love. They may have a dual personality where they can be extremely sweet and loving one moment, but if they feel threatened in their relationship with the reader, they can turn very dangerous and menacing.
Yandere characters in these novels are often extremely possessive. They see the object of their affection as solely belonging to them. For example, they might get angry or even violent if someone else shows interest in their beloved.