Sal Mineo received his first Oscar nomination for portraying Plato in Rebel Without a Cause.
Sal Mineo plays Plato a very much troubled teenager who no longer lives with his family and is instead raised by his black house keeper. He basically spends most of his time alone, and attempts to find some sort of companionship with his fellow troubled teenager Jim, and attempts to help Jim with his problems with the local hoods. One thing that is never said but very much implied is that Plato is rather attracted to Jim to the point that he is clearly suppose to be a homosexual.
This is never stated in the film in anyway not in really even a hidden in the words like some films, instead it basically all comes entirely in Mineo's performance. Mineo is appropriately subtle in his depiction of his character he never plays his character in any sort of flamboyant fashion, instead he suggest this only in his looks, and his body language when reacting with Jim. It is very well handled by Mineo and perfectly shows how Plato is attracted to Jim.
Other than this aspect Plato is a very troubled young man. It actually would have been easy to constantly overplay Plato's troubles, but instead Mineo gives a quietly effective performance that is able to more realistically bring to life Plato's long history of problems. Mineo shows that Plato tries hard to hide all of his problems, but always shows that there is something wrong with him at all times. There is not a single scene where Plato seems entirely normal, because Mineo infuses Plato mental instability in every moment he is on screen.
A very important moment for Plato and Mineo performance is his single really happy scene where he hangs out with Jim in an abandoned home he used to runaway from home to. Mineo makes the most of his scene showing a desperation and a genuine happiness in Plato in this moment. He does not over do it though still making it clear that Plato is not well, but rather Mineo makes this Plato's imperfect attempt to be so.
Interestingly enough for me his final scenes felt like his least impressive scenes. Plato finally goes out of control. In these scenes Mineo is still good and still is as Plato should be, but I really feel that he should perhaps have been able to bring even more emotional strength into this pivotal scene. His performance is very good though I have no doubts about that. He never has a bad moment and creates an excellent characterization.