  We study mergers of ergoregions in $d+1$-dimensional vacuum gravity. At the
merger point, where the ergosurfaces bounding each ergoregion just touch,
solutions exhibit universal behavior when there is rotation only in one plane:
the angle between the merging ergosurfaces depends only on the symmetries of
the solution, not on any other details of the configuration. We show that
universality follows from the fact that the relevant component of Einstein's
equation reduces to Laplace equation at the point of merger. Thus ergoregion
mergers mimic mergers of Newtonian equipotentials and have similar universal
behavior. For solutions with rotation in more than one plane, universality is
lost. We demonstrate universality and non-universality in several explicit
examples.
