  Extensions beyond the Standard Model allow for a gauge singlet scalar to be
kinetically coupled with the Higgs. We consider kinetic mixing between a Dark
scalar gauge singlet \emph{nearly degenerate} with the Higgs, focusing on the
\emph{dynamical} aspects of the mixing phenomena. The renormalization program
is carried out by obtaining the one-loop effective action which yields an
effective non-hermitian Hamiltonian to study the dynamics of mixing. The scalar
Higgs becomes a coherent superposition of the mass eigenstates, thus kinetic
mixing leads to oscillations and common decay channels in striking similarity
with neutral meson mixing. Near degeneracy yields an \emph{enhancement} of the
kinetic coupling. For small kinetic mixing we find that the mass eigenstates
feature different lifetimes which result in a wide separation of time scales of
evolution along with important coherence aspects from Dark scalar-Higgs
interference. The wide separation of scales is manifest as displaced decay
vertices which could potentially be a telltale experimental signal of kinetic
mixing.
