Time-domain astronomy is currently in the limelight thanks to successful high-cadence surveys in operation (e.g., ASAS-SN, CRTS, SkyMapper, ZTF), and the ambitious one in planning (LSST). Our neighbor, M31, provides a favorable ground for exploring the varied variability phenomena in stellar populations of a galaxy. In this talk, I will focus on my exploits of studying variability of massive stars in M31 using the intermediate Palomar Transient Factory survey. In particular, I will present the results of our analysis of M31 Red Supergiants (RSGs)—representing a short-lived and an important stage in the evolution of massive stars—as regards characterizing their variability and their period-luminosity relation. Furthermore, for LSST, meaningful discoveries of novel objects, particularly those that are time-critical, will depend on our ability to rapidly schedule follow-up observations in the face of an unprecedented data rate. I will describe the development efforts being undertaken at NOAO for the event-broker system ANTARES, which will serve to address this challenge, highlighting algorithmic aspects.