2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/121724Special relativistic and strong gravity effects are clearly seen in X-ray energy spectra from AGN. Most important here are the broad profiles of the Fe Kalpha line observed in a large fraction of sources. These indicate that X-ray generation and reprocessing takes place very close to the central black hole. Here we explore consequences of such effects on X-ray variability. We perform computations of a possible quasi-periodic signal from a Keplerian motion of primary X-ray source. We also study in some details the light-bending model of variability of the X-ray reprocessed component, extending previous work on the subject.Conference proceedings to appear in "The Central Engine of Active Galactic Nuclei", ed. L. C. Ho and J.-M. Wang (San Francisco: ASP). 4 pagesAstrophysicstext