  The existence of significant anisotropies in the distributions of the
directions of perihelia and orbital poles of the known extreme trans-Neptunian
objects (ETNOs) has been used to claim that trans-Plutonian planets may exist.
Among the known ETNOs, the pair (474640) 2004 VN112-2013 RF98 stands out. Their
orbital poles and the directions of their perihelia and their velocities at
perihelion/aphelion are separated by a few degrees, but orbital similarity does
not necessarily imply common physical origin. In an attempt to unravel their
physical nature, visible spectroscopy of both targets was obtained using the
OSIRIS camera-spectrograph at the 10.4 m Gran Telescopio Canarias (GTC). From
the spectral analysis, we find that 474640-2013 RF98 have similar spectral
slopes (12 vs. 15 %/0.1um), very different from Sedna's but compatible with
those of (148209) 2000 CR105 and 2012 VP113. These five ETNOs belong to the
group of seven linked to the Planet Nine hypothesis. A dynamical pathway
consistent with these findings is dissociation of a binary asteroid during a
close encounter with a planet and we confirm its plausibility using N-body
simulations. We thus conclude that both the dynamical and spectroscopic
properties of 474640-2013 RF98 favour a genetic link and their current orbits
suggest that the pair was kicked by a perturber near aphelion.
