Many Fallout: New Vegas players assume that siding with Benny is an available option. This isn’t possible. That being said, is there any way to keep Benny alive?
You can keep Benny alive by defeating Caesar’s guards. His binds can be cut off, and he’ll run away.
Benny permanently de-spawns from the game world after exiting the Fort. You won’t be able to work alongside him or speak to him again in any way.
The way to keep Benny alive
The player enters The Fort after receiving an invitation from Caesar. While inside Caesar’s Tent, Benny is seen with his hands tied up. Some players allow Benny to flee from the Tops encounter, either by accident or on purpose.
Caesar allows the player to choose how Benny is dealt with. Should the player choose to save Benny, they’d need to defeat all of Caesar’s guards.
These foes are incredibly strong. The guards are melee-centric and will collapse upon you and drive into a corner. Whether it be through a lot of chems or help from a companion, it’ll be difficult to defeat the mob.
If you’re able to do so, there’s unique dialogue with Benny. He tells the player that he’d disappear if let go, and you’re given the option to cut him loose.
Once Benny is free, he runs from the tent. If you didn’t already clear The Fort out, then the aggravated Legionnaires outside will mow him down.
Let’s say you’ve cleared out the entire Fort before attacking Caesar. Benny will run to the bottom and leave out the main gate, but disappears from the game world.
A cut encounter exists where the freed Benny will approach you in the game world. He’ll tell you to stay down this time, and will fire. It’s impossible to access this cut encounter without altering your game.
By this method, Benny will technically be alive. You won’t be able to join forces with him. Having a set location where he resides and you can at least visit does not exist.
So that’s the answer. You can keep Benny alive by defeating Caesar’s guards.