The Person Profile page ships with blocks that are already set up with Person context. For instance, if you edit the settings for the Person Bio block, you can use the Context syntax in the Custom Content field to access information about the person. Notice that nothing was done to set the context here. This makes the Person Bio block unique. In fact, you can add an HTML block anywhere (any zone, any tab) on the Person Profile and the Context syntax will automatically work for you. You don't have to do any extra configuration.