  The recent associations of neutrinos with blazars require the efficient
interaction of relativistic protons with ambient soft photon fields. However,
along side the neutrinos gamma-ray photons are produced which interact with the
same soft photon fields producing electron-positron pairs. The strength of this
cascade has significant consequences on the photon spectrum in various energy
bands and puts severe constraints on the pion and neutrino production. In this
study, we discuss the influence of the external thermal photon fields
(accretion disk, broad-line region, and dusty torus) on the proton-photon
interactions employing a newly developed time-dependent one-zone hadro-leptonic
code (OneHaLe). We present steady-state cases, as well as a time-dependent
case, where the emission region moves through the jet. Within the limits of
this toy study, the external fields can disrupt the ``usual'' double-humped
blazar spectrum. Similarly, a moving region would cross significant portions of
the jet without reaching the previously-found steady states.

High Energy Astrophysical Phenomena;Astrophysics of Galaxies