  When two black holes merge, the asymmetric emission of gravitational waves
provides an impulse to the merged system; this gravitational wave recoil
velocity can be up to 4000 km s$^{-1}$, easily fast enough for the black hole
to escape its host galaxy. We combine semi-analytic modeling with cosmological
zoom-in simulations of a Milky Way-type galaxy to investigate the role of black
hole spin and gravitational recoil in the epoch of massive black hole seeding.
We sample four different spin distributions (random, aligned, anti-aligned, and
zero spin), and compare the resulting merger rates, occupation fractions, and
MBH-host relations with what is expected by excluding the effect of recoil. The
inclusion of gravitational recoil and MBH spin in the assembly of MBH seeds can
reduce the final $z=5$ MBH mass by up to an order of magnitude. The MBH
occupation fraction, however, remains effectively unaltered due to episodes of
black hole formation following a recoil event. While electromagnetic detections
of these events are unlikely, LISA is ideally suited to detect gravitational
wave signals from such events.
