Ayato Sakamaki- He is a prankster and a very narcissistic boy, always claiming to be the best at everything. Ayato is also very possessive, a pervert, and enjoys seeing his bride suffer.
Laito Sakamaki- Laito acts extremely perverted. His perverted nature caused him to be suspended often from school. He is always cheerful and loves to joke but is similar to Ayato when teasing his bride. However, his personality suddenly changes when something goes against his wishes.
Shu Sakamaki- Apathetic and lazy, Shu is someone who loves nothing but music. He can't stand being with humans, seeing as he sees them as weak and fragile. He is very protective over his bride, though.
Reji Sakamaki- Reiji chooses to be the role model of the house even though he is the second son. Reiji has a very polite attitude and almost always acts like a gentlemen (unless he's dealing with Ayato's behavior or telling someone to be careful not to break the tea cups). Reiji is very tidy with things and wants to keep everything as neat and safe as possible. Although polite, he is a very strict man. Reiji is the one who takes care of the household and of all his younger brothers while Shu, the oldest son, slacks off. Even though he's usually gentle, he is an extreme sadist who uses rather harsh words.
Kanato Sakamaki- Kanato tends to cry often and gets angry when he doesn't get what he wants. He is always demanding for something and wants it right away, and when he doesn't get it, his demeanor changes. That aside, he is quite attached to his bride. Kanato loves to eat sweets, especially cakes. He will not leave his room without bringing his precious Teddy, his best friend, with him. He speaks politely but is abusive and clingy.
Subaru Sakamaki- He is usually alone and never cares about whats happening around him, Subaru is the silent type. He sleeps in a coffin, which is also inside his room. However, he easily gets angry and resorts to violence, going as far as to break everything when he gets extremely angered. He manages to compress this side when around his bride, but is still prone to outbursts. There is a tsundere side of him that only his bride can see. He's a delinquent type, kinda violent and loves to damage things. He's also a sadist, but despite all, can occasionally be sweet.
I got these off wikipedia, but please get the rest of the information off wiki.