We spoke about Keanu Reeves in 'My Own Private Idaho' earlier on in this list, and the fantastic job he did with his performance in the film, but it would all have been to no avail if he didn't have River Phoenix opposite him to play off from. Phoenix, as he always was in everything he did, is totally believable as Mike Waters. The character had a huge impact on gay people and gay culture upon the film's release and represented one of the first depictions of a gay man as a tough guy and an alpha male.
Phoenix always had an element of street-smarts about him, and he brings that to the role, giving life and character to Waters; a street prostitute who treats his occupation as a job and doesn't recognize himself as being gay. The character also has a troubled relationship with drugs, which is a tragic parallel with Phoenix himself.