The Antagonist's secret

Kokichi, nagito and Byakuya the three trio of male antagonists and have a similar shared secret.....there mythical, if you know what I mean....
Like Kokichi who is a trickster and is known for being playful and friendly when you get to know him, like a fox.
Nagito who switches between good and bad but is loyal and loving like a certain wild dog.
And lastly byakuya who is an arrogant man with a family wise beyond their years with a secret kept for years.
they only meet though one person, adoptive motherly sister, Aurora.