  We investigate the interplay between numerical relativity (NR) and
point-particle black hole perturbation theory (ppBHPT) for quasi-circular
non-spinning binary black holes in the intermediate mass ratio regime:
7<=q<=128 (where $q:=m_1/m_2$ is the mass ratio of the binary with m_1 and m_2
being the mass of the primary and secondary black hole respectively).
Initially, we conduct a comprehensive comparison between the dominant (l,m) =
(2,2) mode of the gravitational radiation obtained from state-of-the-art NR
simulations and ppBHPT waveforms along with waveforms generated from recently
developed NR-informed ppBHPT surrogate model, BHPTNRSur1dq1e4. This surrogate
model employs a simple but non-trivial rescaling technique known as the
$\alpha$-$\beta$ scaling to effectively match ppBHPT waveforms to NR in the
comparable mass ratio regime. Subsequently, we analyze the amplitude and
frequency differences between NR and ppBHPT waveforms to investigate the
non-linearities, beyond adiabatic evolution, that are present during the merger
stage of the binary evolution and propose fitting functions to describe these
differences in terms of both the mass ratio and the symmetric mass ratio.
Finally, we assess the performance of the $\alpha$-$\beta$ scaling technique in
the intermediate mass ratio regime.
