Laurence Fishburne portrays the elusive Morpheus who tries to convince Neo (Keanu Reeves) that he is in fact not living in reality. At first Fishburne is heard only over the phone, finding very little about him, until then he finally meets Morpheus in a strange dank room, with Morpheus dressed in black, with even darker sunglasses. I will give Fisburne credit in this scene in that he conveys a great deal of mystery with his delivery of every line, and certainly make the scene very compelling, as well making Morpheus a character you want to learn more about.
As soon as Neo wants to learn more of the truth though, in fact right after he chooses the pill Fishburne completely changes his performance from that of mystery man or mentor. Although to be fair to Fishburne this does fit Morpheus's motivation, since once Neo will join him, he really does not need to draw him anymore, and just needs to train him. Fishburne though drops all the mystery and becomes a tough, but still warm mentor in the film. He handles it well in that as he tells basically the whole plot of the film to Neo he does it with a considerable degree of conviction.
Through the rest of the film he is the Mr. Miyagi offering advice, and training Neo. Fishburne does this well enough always delivery the way he needs to in his role, even if there is anything particularly special about his method though. Later on in the film he has the scene where he is psychologically tortured which again Fishburne does handle well, but it is not exactly an amazing scene. Fishburne is consistently fine in his role from one scene to the next, and fulfills the mentor fairly well. It never amounts to much more than just performing the role well enough.