  XMM-Newton's large field of view and excellent sensitivity have resulted in
hundreds of thousands of serendipitous X-ray detections. Whilst their spectra
have been widely exploited, their variable nature has been little studied. Part
of this is due to the way XMM-Newton currently operates, where observations
generally have a 12 month proprietary period. It is often too late to follow-up
a serendipitous transient a year after detection. New robust software could be
introduced into the pipeline to automatically identify bright transients that
are not the target of the observation. Statistically, hundreds of tidal
disruption events (TDEs) have been detected serendipitously by XMM-Newton. With
prior consent from the PI of the observation, an automatic alert to a new
transient could be set up, allowing it to be followed-up within weeks, ideal
for TDEs that are bright for about a year. Over the next decade, hundreds more
TDEs should be detected. Following-up the brightest in quasi-real time would
allow constraints to be made on the black hole mass, spin and accretion regime
and identify intermediate-mass black holes that are expected to be hidden in
faint, low-mass galaxies. This article discusses the advantages that such
changes would have on the follow-up of transients and TDEs.
