  The blazar PKS 1510-089 was the first of the flat spectrum radio quasar type,
which had been detected simultaneously by a ground based Cherenkov telescope
(H.E.S.S.) and the LAT instrument on board the Fermi satellite. Given the
strong broad line region emission defining this blazar class, and the resulting
high optical depth for VHE ($E>100\,$GeV) $\gamma$-rays, it was surprising to
detect VHE emission from such an object. In May 2015, PKS 1510-089 exhibited
high states throughout the electromagnetic spectrum. Target of Opportunity
observations with the H.E.S.S. experiment revealed strong and unprecedented
variability of this source. Comparison with the lightcurves obtained with the
\textit{Fermi}-LAT in HE $\gamma$-rays ($100\,$MeV$<E<100\,$GeV) and ATOM in
the optical band shows a complex relationship between these energy bands. This
points to a complex structure of the emission region, since the one-zone model
has difficulties to reproduce the source behavior even when taking into account
absorption by ambient soft photon fields. It will be shown that the presented
results have important consequences for the explanation of FSRQ spectra and
lightcurves, since the emission region cannot be located deep inside the broad
line region as is typically assumed. Additionally, acceleration and cooling
processes must be strongly time-dependent in order to account for the observed
variability patterns.
