Athena gave Perseus a polished shield, and Hermes gave Perseus a sword to attack Medusa with.
No one acted as a mirror for Perseus. Athena's polished shield acted as a mirror for Perseus though.
Odysseus and Perseus
Athena
Grover and Athena.
They were not. Athena was a virgin goddess and goddess of heroic deeds.
Athena and Hermes
Athena
Athena and Hermes
Athena's demi-god siblings are Helena, Perseus, and Hercules.
When Perseus gave Athena Medusa's head, she put it on her shield.
He was favored by both Hermes and Athena.