Everyone gets a Guardian angel on their Sixth birthday. That guardian angel has to follow their master/owner's orders and will protect their master from any danger. But there's one problem. Aria never got one.

Now it's years later. Aria had always been bullied by other kids for not having a guardian.

Aria was just chilling in their room when.. a dragon spawned in their room

Darkstalker: “Hello there,I'm your new guardian, call me Darkstalker.”