  We relate the fundamental quadrupolar fluid mode of isolated non-rotating NSs
and the dominant oscillation frequency of neutron star merger remnants. Both
frequencies individually are known to correlate with certain stellar parameters
like radii or the tidal deformability, which we further investigate by
constructing fit formulae and quantifying the scatter of the data points from
those relations. Furthermore, we compare how individual data points deviate
from the corresponding fit to all data points. Considering this point-to-point
scatter we uncover a striking similarity between the frequency deviations of
perturbative data for isolated NSs and of oscillation frequencies of rapidly
rotating, hot, massive merger remnants. The correspondence of frequency
deviations in these very different stellar systems points to an underlying
mechanism and EoS information being encoded in the frequency deviation. We
trace the frequency scatter back to deviations of the tidal Love number from an
average tidal Love number for a given stellar compactness. Our results thus
indicate a possibility to break the degeneracy between NS radii, tidal
deformability and tidal Love number. We also relate frequency deviations to the
derivative of the tidal deformability with respect to mass. Our findings
generally highlight a possibility to improve GW asteroseismology relations
where the systematic behavior of frequency deviations is employed to reduce the
scatter in such relationships and consequently increase the measurement
accuracy. In addition, we relate the f-mode frequency of static stars and the
dominant GW frequency of merger remnants. We find an analytic mapping to
connect the masses of both stellar systems, which yields particularly accurate
mass-independent relations between both frequencies and between the postmerger
frequency and the tidal deformability.
