Perhaps this is a bit of a naive question, but I'm having trouble with the following issue. It is easy to describe the motion of a test particle near a black hole using classical general relativity. The underlying assumption is that gravity is a geometric manifestation, and the orbits are geodesics. The test particle does not directly interact with the black hole, only the spacetime curvature. From the quantum gravity perspective, however, gravitational interactions are mediated by graviton exchange between two masses. In the case of black holes, what is the graviton source? Are they emitted from the horizon? (since clearly they cannot come from the interior). Any insight or pointers to appropriate literature would be appreciated.