  We present stellar dynamical models of the lopsided, double-peaked nucleus of
M31, derived from Hubble Space Telescope (HST) photometry. A Schwarzscild-type
method, in conjunction with Richardson-Lucy deconvolution, was employed to
construct steadily rotating, hot, stellar disks. The stars orbit a massive dark
object, on prograde and retrograde quasi-periodic loop orbits. Our results
support Tremaine's eccentric disk model, extended to include a more massive
disk, non zero pattern speed ($\Omega$), and different viewing angle. Most of
the disk mass populated prograde orbits, with $\simeq 3.4%$ on retrograde
orbits. The best fits to photometric and kinematic maps were disks with
$\Omega\approx 16\kmspc $. We speculate on the origins of the lopsidedness,
invoking recent work on the linear overstability of nearly Keplerian disks,
that possess even a small amount of a counter-rotating component. Accretion of
material-no more massive than a globular cluster-onto a preexisting stellar
disk, will account for the mass in our retrograde orbits, and could have
stimulated the lopsidedness seen in the nucleus of M31.
