If that's not a huge clue, right? He is Ryuk. The Shinigami catalyst of Death Note. He drops the Death Note into the human world to kill the boredom. He enjoys every minute on Earth, especially the apples. Withdrawal symptoms of his apple addiction causes him to twist into a pretzel shape.
He and Light get along as well as can be expected for a serial killer genius and snide death god.
He is the one to get revenge for Maes' death by burning alive the homunculus that killed him. To say you have to be powerful to do this is an extreme understatement.
He comes across as a ladies man and a procrastinating slacker who is also power hungry, but that is a facade for his true character. He uses his power to protect those that cannot protect themselves.
His time in the Ishval war haunts him.
Edward is his direct subordinate and they both have a mutual respect for each other while having a rocky relationship.