Interesting guy, Sulla. His Wikipedia page gives you a starting point, but you can't really grasp Sulla from an objective point of view. He did a lot of things in his life, and made a lot of enemies, and a lot of friends.
At any given point, he'll do something really awful and seemingly incredibly self-centered and unjustified, and he'll seem like a real terrible human being
And then he'll turn around and do something really magnificent, brave, generous, honest, and selfless.
Hard to make sense of him. To really get a grasp of him, you need to look at him from a mix of perspectives -- from the perspective of Mithradates, the King of Pontus who fought against him in bitter struggle, from the Marian faction, from contemporaries and recent historians, and from people looking back through various ages.
One of the more interesting statements by him is his last words -- he wrote his own epitaph when he knew he was dying --
"No friend ever served me, and no enemy ever wronged me, whom I have not repaid in full."
Maybe the most interesting thing about Sulla is you always get the sense from him that he felt wholly in control of his own destiny at all times, and that things going wrong were temporary setbacks to be overcome. And he did. He overcame them all.
He did some inhumane and horrible things, and he did some magnificent and benevolent things. He's hard to make sense of. But he's worth studying up on just for the sheer force of will and gravity you get from learning about his life.