Faults release tectonic strain through a wide and complex spectrum of slip behaviors, including aseismic creep, episodic slow-slip events and earthquakes. Field observations, seismological and geodetic data, laboratory experiments, and numerical modelling have shown that a range of factors, including structural and geometrical complexity, mechanical and rheological heterogeneities, fluid pressure and chemistry, and temperature, all interact across spatial and temporal scales to govern fault slip behavior. Yet, understanding how these interconnected factors control the occurrence of different slip modes and the transitions between them remains one of the fundamental challenges in earthquake science. This session welcomes contributions that investigate the wide range of fault slip behaviors using multidisciplinary and multiscale approaches, including field observations, structural and microstructural analyses, laboratory rock deformation experiments, geochemical and hydrological characterization of fault fluids, seismological and geodetic observations of active faults, and numerical modelling. We aim to foster discussion on the physicochemical and mechanical processes controlling fault strength, slip stability, rupture nucleation and propagation, and the evolution of fault zone geometry across the seismic cycle. By bringing together complementary perspectives across scales, this session seeks to improve seismic hazard assessment and our understanding of the mechanics of faulting and earthquakes.