  The Pluto-Charon binary system is the best-studied representative of the
binary Kuiper-belt population. Its origins are vital to understanding the
formation of other Kupier-belt objects (KBO) and binaries, and the evolution of
the outer solar-system. The Pluto-Charon system is believed to form following a
giant impact between two massive KBOs at relatively low velocities. However,
the likelihood of a random direct collision between two of the most massive
KBOs is low, and is further constrained by the requirement of a low-velocity
collision, making this a potentially fine-tuned scenario. Here we expand our
previous studies and suggest that the proto-Pluto-Charon system was formed as a
highly inclined wide-binary, which was then driven through
secular/quasi-secular evolution into a direct impact. Since wide-binaries are
ubiquitous in the Kuiper-belt with many expected to be highly inclined, our
scenario is expected to be robust. We use analytic tools and few-body
simulations of the triple Sun-(proto-)Pluto-Charon system to show that a large
parameter-space of initial conditions leads to such collisions. The velocity of
such an impact is the escape velocity of a bound system, which naturally
explains the low-velocity impact. The dynamical evolution and the origins of
the Pluto-Charon system could therefore be traced to similar secular origins as
those of other binaries and contact-binaries (e.g. Arrokoth), and suggest they
play a key role in the evolution of KBOs.
