Arioch
Arioch loves his job; creating chaos and encouraging revenge is fun, and if he pranks a few demons, angels, and humans along the way, all the better. When an archangel shows up with a message from god, Arioch knows he ought to take it seriously, but what's the fun in that? Michael, the human he's supposed to help, takes everything seriously enough for both of them, and Arioch is determined to teach the guy how to have a little fun with life. If he starts to fall for the human along the way, well, another human-demon pairing can only cause more chaos, which is definitely Ari's specialty. Now he just has to convince Michael that although the two of them are polar opposites, they actually work perfectly together.
Michael
Michael has been the dependable, practical older brother his entire life; he took the weight of the world on his shoulders when he was too young to realize how heavy the burden would be. If he can guarantee happiness for his siblings, that will be enough for him, even if all he can see in his own future is loneliness. However, when Michael realizes that someone from the afterlife lied to him and attempted to cause his family harm, he is determined to do something about it. With the help of a certain demon, maybe he can figure out who targeted his family and get a little revenge. He'll just have to refrain from killing the demon that is messing up his perfectly ordered existence. When the cheerful prankster actually starts looking attractive to Michael, maybe he'll finally step out of his comfort zone and find out how fun chaos can actually be.