Character Analysis
Joshua is the adopted African "son" of Clive. We're definitely using the word son sarcastically here, because Joshua is actually just a servant living in Clive's house. Churchill makes the choice of casting a white person to play Joshua, and from the moment Clive says in Act 1, "You'd hardly notice the fellow was black" (1.1.23), it comes as a shock to the audience. But it also shows how much Joshua himself has (ostensibly) embraced the idea of white superiority, responding, "My skin is black but oh my soul is white" (1.1.24).
Even though Joshua constantly declares his loyalty to white people, there are little hints that he might not be as loyal as Clive thinks. For example, Joshua tends to talk back to Clive's wife, Betty, and to disobey her when Clive isn't around. Now you could just say that this is because Joshua only respects Clive as the man of the house. But then you'd have to account for the fact that, at the end of Act 1, Joshua lifts his gun and points it at Clive. We never actually see him fire the gun, but the act of aiming it definitely suggests that there's a silent anger in Joshua that's been pushed beneath the surface.
Joshua's Timeline