  We investigate and classify Fermi surface behavior for a set of fermionic
modes in a family of backgrounds holographically dual to N=4 Super-Yang-Mills
theory at zero temperature with two distinct chemical potentials. We
numerically solve fluctuation equations for every spin-1/2 field in
five-dimensional maximally supersymmetric gauged supergravity not mixing with
gravitini. Different modes manifest two, one or zero Fermi surface
singularities, all associated to non-Fermi liquids, and we calculate dispersion
relations and widths of excitations. We study two limits where the
zero-temperature entropy vanishes. In one limit, a Fermi surface approaches a
marginal Fermi liquid, which we demonstrate analytically, and conductivity
calculations show a hard gap with the current dual to the active gauge field
superconducting, while the other is insulating. In the other limit,
conductivities reveal a soft gap with the roles of the gauge fields reversed.
