How is Dark Messiah connected to Heroes of Might and Magic?

Agrail rejected his dark side, and I don't think he intended to return to the Overlord, let alone imply that "not everything is lost" with the phrase "Call me Agrail."

I'm talking about how the Overlord perceived it, not what Agrail meant. It became clear that Agrail wasn't the sharpest tool in the shed when his taste in women was revealed.