Once Perseus arrived at Medusas lair he immediately saw statues. The statues were the victims who stared into Medusas eyes, once alive and now turned to stone. Perseus cautiously made his way through to find Medusa.
As he enters he turns around and looked into the reflection of his shield to not look into medusas eyes if seen. walking backward through the lair he spotted medusa sleeping. He decided to take the change to cut her head off and slew her in her sleep.
With eyes closed, he placed Medusas head into his bag. As he looked back at the corpse of Medusa he saw Pegasus and Chrysaor be born from her body. He was amazed.
As Perseus started his depart from Medusas lair he heard a sound
Its was medusas, sisters, chasing him, attempting to avenge Medusa. he just barely escaped.