Holding the Abandoned Teddy ends the fight peacefully, and doing so will cause her to drop Keeper's Circlet. Attempting to summon her after doing this will instead summon the Keeper's Spirit.
The Keeper’s true name is “Octavia”, this name can be seen as the player ends the fight peacefully using the Abandoned Teddy while a mysterious entity says her name
The Keeper spawns either randomly at night after defeating the Eye of Cthulhu, with the message "Shrieks echo through the night..."