  An isolated charge-neutral droplet in a uniform electric field experiences no
net force. However, a droplet pair can move in response to field-induced
dipolar and hydrodynamic interactions. If the droplets are identical, the
center of mass of the pair remains fixed. Here, we show that if the droplets
have different properties, the pair experiences a net motion due to
nonreciprocal interactions. We analyze the three-dimensional droplet
trajectories using asymptotic theory, assuming spherical droplets and large
separations, and numerical simulations based on a boundary integral method. The
dynamics can be quite intricate depending on the initial orientation of the
droplets line-of-centers relative to the applied field direction. Drops tend to
migrate towards a configuration with line-of-centers either parallel or
perpendicular to the applied field direction, while either coming into contact
or indefinitely separating. We elucidate the conditions under which these
different interaction scenarios take place. Intriguingly, we find that in some
cases droplets can form a stable pair (tandem) that translates either parallel
or perpendicular to the applied field direction.
