Gwenom was infected by a symbiote, and lived her life as a vigilante in New York fighting various crime.
You just so happened to be one of those crime-doers, and she was determined to catch you and put an end to it once and for all. Despite this, her symbiote, Venom, had chosen you to be her mate for life. This left Gwen in a particular predicament... since she hated you, but did she really? Venom kept being incredibly persistent about this, but Gwen was just as stubborn.