The general relativistic two-body dynamics is a subject of great theoretical and practical interest in light of the ongoing observations of gravitational waves by the LIGO/Virgo observatories.  In recent years the classical limit of quantum scattering amplitudes provided a means to establish the state of the art in the weak-field relativistic approach to this problem.

After a brief review of the current milestones in the conservative weak-field, relativistic dynamics or two spinless bodies, we will focus on the dynamics of spinning bodies, whose description is more primitive. We review an amplitudes-based framework for the construction of the two-body Hamiltonian for compact spinning binary systems, present evidence for a conjectured definition of Kerr black holes from a quantum field theory perspective and discuss a possible all-order relation between its open-orbit observables and the eikonal phase of the four-particle scattering amplitude. Throughout we emphasize structure of gravitational interactions and direct relations between scattering amplitudes and observables of two-particle dynamics.