Because he is very smart, cunning, can think on his feet and never panics. He is quite possibly the smartest person serving time in Oz. Whether or not he is the most intelligent is another story. He didn't belong to any gang, he was by himself for the most part, minus his brother Cyril whom he had to look out for. But Ryan knew what everyone wanted, he would make friends in high places on both sides of the fence and in every ethnic group by dealing drugs to them, tipping them off, keeping his ears open to gain information to barter with. Though he would not shy from betraying one person or another if it meant risking his being found out or killed by staying silent. The most unique thing about how he lies, is that there's about 90% truth to what he says, he twists facts to help deny his involvement, which makes it extremely difficult to tell whether he is lying or not and he's persuasive enough to get people to believe him. Also, he insulates himself from doing the dirty work, if someone asks him to kill someone, or if he needs someone killed; He creates a set of circumstances where he either convinces someone to kill the person or extorts someone into doing the deed. [For example: In season 2, Ryan tries to have Schillinger killed. So he asks Jazz to slip a package through the mail room for him. Then Ryan tells one of his friends in the gym "Hey man, I'm having a package slipped through" but made sure one of the Aryans was in ears shot, so he would run and tell Schillinger. Sure enough, that's what happened and Jazz gets caught trying to slip brass knuckles through the mail room, leading to him being punished. So Ryan says to Jazz "I thought you and Schillinger were friends. If I was you, I'd teach that fuck a lesson." Which convinced Jazz to make an attempt on Schillinger. Which of course completely insulated O'Reilly from killing Schillinger had Jazz succeeded.