Mycenae, differently from other Gold Saints, knew something was off but was bounded by his loyalty and promise to a friend. Good stuff.
The end gave me the feeling Mycenae is targeting Medea now. Not only for giving up on Eden, but it seems he's suspicious about Medea and her influence over Mars. I mean, Ludwig had a similar goal, but was clearly human and apparently level-headed, and we don't know exactly what made him the way he is now.
And speaking of Ludwig..
That was the name of a Silver Saint brought back by Hades' power. Probably just a reference, but still fun.