  We investigate the origins of the photometrically Very Red and Less Red
Trans-Neptunian Objects. We first reanalyse the dataset of Marsset et al. 2019
and find that, in addition to the known color-inclination correlation in hot
TNOs, a similar trend exists for color-eccentricity. We show that VR TNOs are
sharply constrained to eccentricities < 0.42 and inclinations < 21 deg, leading
to a paucity of VR scattered disk and distant MMR objects. We then interpret
these findings using N-body simulations accounting for Neptune's outward
migration into a massless particles disk, and find that these observations are
best reproduced with a LR-to-VR color transition line between 38 and 42 AU in
the primordial disk, separating the objects' formation locations. For an
initial surface density profile $\Sigma \propto 1/r^2$, a color transition
around 38 AU is needed to explain the high abundance of VR plutinos but creates
too many VR scattered disk objects, while a transition line around 42 AU seems
to better reproduces the scattered disk colors but creates virtually no VR
plutinos. Our simulations furthermore show that the rarity of VR particles at
high eccentricity is possibly due to the absence of sweeping higher order MMRs,
and secular resonances, beyond 42 AU. Inspecting individual populations, we
show that the majority of VR SDOs originate as objects trapped in Neptune's
second and third order MMRs. These then evolve due to diffusion, scattering,
Kozai-Lidov cycles, and secular resonances into their current orbits. Future
unbiased color surveys are crucial to better constrain the TNOs dynamical
origins.
