  We propose a self-interacting dark matter (DM) scenario with right handed
neutrino (RHN) portal to the standard model (SM). The dark sector consists of a
particle DM, assumed to be a Dirac fermion, and a light mediator in terms of a
dark Abelian vector boson to give rise to the required velocity dependent
self-interactions in agreement with astrophysical observations. Irrespective of
thermal or non-thermal production of such a DM, its final relic remains
under-abundant due to efficient annihilation rates of DM into light mediators
by virtue of large self-interaction coupling. We then show that a feeble portal
of DM-SM interaction via RHN offers a possibility to fill the relic deficit of
DM via the late decay of RHN. As RHN also arises naturally in seesaw models
explaining the origin of light neutrino masses, we outline two UV complete
realizations of the minimal setup in terms of scotogenic and gauged B-L
frameworks where connection to neutrino mass and other phenomenology like
complementary discovery prospects are discussed.
