  Investigations into Hawking radiation often assume a black hole model
featuring an event horizon, despite the growing consensus that such causal
structures may not exist in nature. While this assumption is not crucial for
deriving the local properties of radiation at future null infinity, it plays a
significant role in discussions about Hawking partners -- the field modes that
purify Hawking radiation. This article aims to explore the definition and fate
of Hawking partners in black hole scenarios where semiclassical mass loss due
to Hawking radiation is considered. Our analysis avoids the assumption of event
horizons and instead focuses on collapse processes that feature a trapped
region bounded by a dynamical horizon. We derive the form of the partners,
accounting for the effects of back-scattering. Furthermore, using these results
and mild assumptions, we find that Hawking partners cannot "leak" out of the
dynamical horizon to partially purify the Hawking radiation in the regime where
general relativity coexists semiclassically with quantum field theory. This
finding emphasizes the necessity for new physics, such as quantum gravity, to
resolve the final fate of information.
