How to unlock: After entering the Vault 81 (Vault 81 quest) (M6,3).
A little girl named Erin Combes has lost her cat Ashes (you probably walked next to him when you entered the vault). You must find the animal. You can bargain with the girl, but it will not change the reward. You will find her in the room - the next door near the school.
The cat can be found outside, on the sidewalk next to the pond. You must simply "talk" to the animal and it will return to the vault. Now you must return and talk to the girl.
Quest rewards: Teddy Bear, small number of experience points, the Hole in the Wall quest.