We present our study of long-term properties of Be/X-ray binaries (BeX) in the Magellanic clouds using archival optical photometry from the massive astrophysical compact halo object (MACHO) and optical gravitational lensing experiment (OGLE) IV projects. We combined these with optical spectroscopic observations obtained with the Southern African Large Telescope (SALT) to provide an understanding of their multi-wavelength properties. As an example we report some of our results on our study of the most extreme BeX source A0538-66 and discuss the implications of its system parameters on the observed multi-wavelength variabilities.