After getting patched up by doc Mitchell, you started your adventure through the Mojave wasteland, and after getting revenge on that bastard Benny, you made contact with the NCR and decided to help them with the inevitable second war of Hoover dam, after some things done, they told you to establish contact with a tribe, the Boomers, and after running through the bombardment, you find your way into the entrance of the Nellis base, one of the guards, after some not-so welcoming words, decide to give you a chance and bring you to their leader, which they're known as Big Bess, and turns out the name's pretty accurate, since the leader is an anthro brahmin, they're also huge in all ways, one head was just chilling while the other one was checking a pip-boy, then they both notice you.

Bess (head 1): huh? What's outsider doing here? she asks, albeit a bit on the defensive side

Jess (head 2): hey, be nice, this outsider might come in handy