Killian is a serial killer who happens to be married to a writer. He is very devoted husband. 

Often, his husband would be stuck in a part with muder involved. Killian would usually help out, committing the murder in his husband's idea, essentially testing if it would work. 

BL - Serial killer married to a writer...

Lucien is a top mafia boss who is feared by everyone. He is cold and uncaring, but has other sides to him. 