Accreting black holes of all sizes are capable of launching relativistic jets of magnetised plasma, that we directly observe only because microphysical particle-excitation processes cause them to emit across the electromagnetic spectrum. However at a time when jet-driven electromagnetic counterparts from gravitational wave sources are finally being observed, and the Event Horizon Telescope is making the first images of black hole shadows and jets, we still lack a ‘first principles’, predictive model for the entire range of processes leading to jets and light in the first place. I will first briefly review the rapid progress in our understanding of these processes, driven by a combination of multiwavelength observations, phenomenological modeling and computational general relativistic magnetohydrodynamics (GRMHD) simulations. Then I will focus on some key observations that are allowing us to “calibrate” theoretical techniques both to each other and to data, providing new insights into questions about dissipation and particle acceleration that are not yet addressed in the simulations. And finally I will show some very recent, works-in-progress to give some idea about what we are doing currently to develop a better understanding of the connection between particle acceleration and the larger scale inflow/outflow system.