  We discuss the possibility of thermal flares in centers of AGNs and
microquasars. We present preliminary results of an ongoing study trying to
assess the feasibility of a hypothesis suggesting that certain flares observed
in these sources originate in the very centers of the systems and not in the
relativistic jets. Using a simple toy model we reproduce optical flares with
lightcurves very similar to those observed in the sources. The model suits
especially well those cases where only the latter peak of a double-peaked
optical flare has a radio counterpart.
