After running for over three years at a world-record collision energy of 13 TeV, the Large Hadron Collider (LHC) completed its Run-2 dataset last December. This new dataset offers an unprecedented opportunity to test a wide range of theories which, if true, would address questions that remain unanswered in the otherwise well-established Standard Model of particle physics. However, such gains in explanatory power hinge entirely on the existence of new fundamental quantum fields and their associated particles whose decay signatures can be recorded in the ATLAS detector. In particular, a decay signature involving a pair of high energy electrons or muons (dilepton) is theoretically and even historically well motivated, and has recently been investigated using the leverage of the full Run-2 dataset. In my presentation I will touch on these theoretical motivations and then detail the procedure and results of the latest search for exotic particles producing dilepton signatures in data collected with the ATLAS detector. I will also explain what the findings represent in the wider context of searches at the LHC and how they help guide theoretical developments toward a better description of particle physics.