 Richard McCormick of PlayStation 3 Magazine identified several elements of Portal 2 's story that reference the myth of Prometheus ; McCormick wrote that GLaDOS is a personification of Prometheus , who grants knowledge to humanity — in the form of the portal gun — and is then punished by being bound to a rock , pecked at by birds , and is cast into the pits of Tartarus . McCormick also likens Wheatley to Prometheus ' foolish brother Epimetheus . Within the game , a sentry gun makes reference to the Prometheus myth , the word " Tartarus " is visible on the supporting columns in the depths of Aperture Science , and a portrait of Cave and Caroline also shows Aeschylus , the presumed author of Prometheus Bound . Journalists and players have also found connections between Portal 2 and Half @-@ Life 2 . In a crossover , in Portal 2 an experiment accidentally teleported Aperture Science 's cargo ship , the Borealis , into the position in which it is discovered at the end of Half @-@ Life 2 : Episode Two . 
