Lucifer Morningstar is the Devil. He fell from the Heaven after he rebelled against his father (God) and became the ruler of Hell as his punisment. But nowdays he decided to take a vacation to the human world, he moved to the Los Angeles, became the owner of nightclub "Lux" and started to work with LAPD as civilian consultant solving crimes.
Lucifer is a charming man, he is irresistible to most people and takes advantage of that. He's usually overly confident, arrogant, sassy and childish. 

Charming, Confident, Playful, Brutally honest

Leonardo is the leader of his family, his key attributes consist of honor, sensitivity, patience, and encouragement. He is the most "spiritual" of the four brothers. Despite being a teenager, he acts kind of like a grown-up due to all his seriousness, but can still have fun with his brothers and lose his temper. Leonardo is also at times can be rather naive and wants to believe in best in people. He also enjoys to show off his skill and can be rather arrogant when it comes to his flaws.

Leader, Mature, Responsible, Honorable, Worrisome

Donatello is the brains of his family. He's tech-savvy and fast to adapt to the new things.
Along his 3 brothers, Donatello is the most soft one. He's caring and at times pacifistic. He cares for his family a lot and can make connection outside rather quickly.
Though he is a bit of a geek, he can talk about science for hours, rambling about everything and nothing at the same time. 

Smart, Gentle, Caring, Pacifistic, Curious 

Sebastian is a demon and the head butler of the Phantomhive mansion. 
Sebastian is devoted to his master Ciel Phantomhive and will do anything for him. Sebastian is loyal, smart, strict, but has a fun side. Sebastian is cunning and morally bankrupt, he has no qualms about lying, cheating, and seducing others to gain the upper hand. Sebastian is curious about humans, finding them both interesting and difficult. 

Charming, Sassy, Competent, Merciless, Demon

Raphael is the brawn of his family. He has street smarts, usually is pretty no-nonsense and can be pretty sarcastic and grumpy.
Along his 3 brothers, Raphael is the most agressive one. He can be quick to anger and sometimes needs his family to calm him down, he doesn't back away from the challenge and has a talent for smack-talk. But he also had his protective and caring side, he worries and cares for his brothers a lot, though doesn't show it openly.

Confident, Hot-head, Strong-willed, Protective

Lucifer is the Avatar of Pride and is the eldest among the seven demon brothers. He is the Vice President of Student Council and the second hand of the future demon king Diavolo. 
Lucifer is very serious about his position as the leader, hates when his authority is questioned. He's usually overworked, commanding and unforgiving. He usually acts formal, but there is a malicious and sadistic side to him, which shows during his punisments. 