  After the successful detection of cosmic high-energy neutrinos, the field of
multiwavelength photon studies of active galactic nuclei (AGN) is entering an
exciting new phase. The first hint of a possible neutrino signal from the
blazar TXS 0506+056 leads to the anticipation that AGN could soon be identified
as point sources of high-energy neutrino radiation, representing another
messenger signature besides the well-established photon signature. To
understand the complex flaring behavior at multiwavelengths, a genuine
theoretical understanding needs to be developed. These observations of the
electromagnetic spectrum and neutrinos can only be interpreted fully when the
charged, relativistic particles responsible for the different emissions are
modeled properly. The description of the propagation of cosmic rays in a
magnetized plasma is a complex question that can only be answered when
analysing the transport regimes of cosmic rays in a quantitative way. In this
paper, we therefore present a quantitative analysis of the propagation regimes
of cosmic rays in the approach that is most commonly used to model non-thermal
emission signatures from blazars, i.e. the existence of a high-energy
cosmic-ray population in a relativistic plasmoid traveling along the jet axis.
In this paper, we show that in the considered energy range of high-energy
photon and neutrino emission, the transition between diffusive and ballistic
propagation takes place, significantly influencing not only the spectral energy
distribution but also the lightcurve of blazar flares.
