Pre-CK mod...

It's a follower named Diane.

Go to Vault 111 exterior and click on Diane in console(don't worry if she is in a frozen statuelike state)
Use the console command :

(After clicking on her)

"bat diane"


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to get Diane to follow you around.




To load the mod into the game edit this file:

C:\Users\\AppData\Local\Fallout4\plugins.txt

...and add Diane.esp to the list of mods to load. Make sure to mark the file as read-only after you edit it!

or Use a mod manager.