Remember that bit about Andromeda’s parents not allowing the marriage if Perseus didn’t negotiate first? Well, they even tried to break the bargain. In fact, they invited the guy they wanted Andromeda to marry, a man named Agenor. Andromeda’s parents even claimed that Perseus forced them into the agreement to marriage, despite Agenor having a prior claim.
Agenor’s man immediately attacked. Now, when I say his men, I’m not talking about his table at the wedding. We’re talking 200+ armed soldiers going for Perseus en masse. Oh, and Cassiopeia is yelling out “Perseus must die!” Mother-in-laws, right?
Fortunately, Perseus decides to not try to slaughter them all in hand-to-hand combat (just some) so he goes nuclear with Medusa’s head. It’s funny how the nuclear option can end disagreements so quickly.
What’s not funny is how adamant and intent Andromeda’s parents were on reneging on their agreement and even wanted to murder Perseus. There’s no discussion as to why Agenor is the preferred suitor for Andromeda, other than that’s the one they chose. Personally, I’d be inclined to think that the man who saves my daughter is pretty okay, especially if it was one of my screw-ups that put her in danger.
There is a distinct thread in the myths of Perseus regarding family values. Perseus’s grandfather casts him out, a man threatens to marry Danae against her will, and Andromeda’s parents not only cause her danger, but also attempt to kill the man who saves her. It appears that everyone but Perseus has no regard for family values.