  Young stars show a variety of highly energetic phenomena, from accretion and
outflow processes to hot coronal plasmas confined in their outer atmosphere,
all regulated by the intense stellar magnetic fields. Many aspects on each of
these phenomena are debated, but, most notably, their complex mutual
interaction remains obscure. In this work I report how these phenomena are
simultaneously responsible for the high-energy emission from young stars, with
a special focus on the expected and observed variability in the X-ray band.
Investigating variations in the X-ray emission from young stars allows us to
pose constraints on flare and coronal plasma properties, coronal heating,
accretion stream properties, and accretion geometries. All these results are
important building blocks for constructing a comprehensive picture of the
complex magnetosphere of young stars.
