  Changing-look active galactic nuclei (AGNs) present an important laboratory
to understand the origin and physical properties of the broad-line region
(BLR). We investigate follow-up optical spectroscopy spanning $\sim 500$ days
after the outburst of the changing-look AGN 1ES\,1927+654. The emission lines
displayed dramatic, systematic variations in intensity, velocity width,
velocity shift, and symmetry. Analysis of optical spectra and multi-band images
indicate that the host galaxy contains a pseudobulge and a total stellar mass
of $3.56_{-0.35}^{+0.38} \times 10^{9}\, M_\odot$. Enhanced continuum radiation
from the outburst produced an accretion disk wind, which condensed into BLR
clouds in the region above and below the temporary eccentric disk. Broad Balmer
lines emerged $\sim 100$ days after the outburst, together with an unexpected,
additional component of narrow-line emission. The newly formed BLR clouds then
traveled along a similar eccentric orbit ($e \approx 0.6$). The Balmer
decrement of the BLR increased by a factor of $\sim 4-5$ as a result of secular
changes in cloud density. The drop in density at late times allowed the
production of \hei\ and \heii\ emission. The mass of the black hole cannot be
derived from the broad emission lines because the BLR is not virialized.
Instead, we use the stellar properties of the host galaxy to estimate
$M_\mathrm{BH} = 1.38_{-0.66}^{+1.25} \times 10^{6}\, M_\odot$. The nucleus
reached near or above its Eddington limit during the peak of the outburst. We
discuss the nature of the changing-look AGN 1ES\,1927+654 in the context of
other tidal disruption events.
