  The Standard Model of particle physics predicts the speed of light to be a
universal speed of propagation of massless carriers. However, other
possibilities exist -- including Lorentz-violating theories -- where different
fundamental fields travel at different speeds. Black holes are interesting
probes of such physics, as distinct fields would probe different horizons.
Here, we build an exact spacetime for two interacting scalar fields which have
different propagation speeds. One of these fields is able to probe the black
hole interior of the other, giving rise to energy extraction from the black
hole and a characteristic late-time relaxation. Our results provide further
stimulus to the search for extra degrees of freedom, black hole instability,
and extra ringdown modes in gravitational-wave events.
