  Context. V838 Monocerotis is a peculiar binary that underwent an immense
stellar explosion in 2002, leaving behind an expanding cool supergiant and a
hot B3V companion. Five years after the outburst, the B3V companion disappeared
from view, and so far did not recover. Aims. We investigate the changes in the
light curve and spectral features Methods. A monitoring campaign has been
performed during the past 13 years with the Nordic Optical Telescope to obtain
optical photometric and spectroscopic data. The data sets are used to analyse
the temporal evolution of the spectral features and the spectral energy
distribution, and to characterize the object. Results. Our photometric data
show a steady brightening in all bands during the past 13 years, which is
particularly prominent in the blue. This rise is also reflected in the spectra,
showing a gradual relative increase in the continuum flux at shorter
wavelengths. In addition, a slow brightening of the Ha emission line starting
in 2015 was detected. These changes might imply that the B3V companion is
slowly reappearing. During the same time interval, our analysis reveals a
considerable change in the observed colours of the object along with a steady
decrease in the strength and width of molecular absorption bands in our
low-resolution spectra. These changes suggest a rising temperature of the cool
supergiant along with a weakening of its wind, most likely combined with a slow
recovery of the secondary due to the evaporation of the dust and accretion of
the material from the shell in which the hot companion is embedded. From our
medium-resolution spectra, we find that the heliocentric radial velocity of the
atomic absorption line of TiI 6556.06 A has been stable for more than a decade.
We propose that TiI lines are tracing the velocity of the red supergiant in
V838 Mon, and not representing the infalling matter as previously stated.
