>>531053064
Medusa was cursed by Athena for, depending on the version: Being prettier than her and thus pissing Athena off.
Being raped by Poseidon in one of her temples and pissing her off.
One version I found had her pissing off Athena by refusing to marry some man that was found for her in a temple too and this was considered a sign of arrogance.
After Medusa was decapitated her head was stuck on Athena's shield further tying the two together in myth.