Who is Thrasybulus from The Politics of Aristotle and what is their importance?

This is a man who intentionally established himself in an influential relationship with another man for the purposes of securing political standing. He made an effort to turn Gelon's son, into a sensualist. Apparently, Thrasybulus believed that if he could control Gelon's lifestyle in this manner then he would also be able to lead him in politics or secure for himself a heightened degree of power.