So, I finally managed to get into Nellis Air Force Base half blown up. I didn't have my companion follow because....well, I didn't want her to die.

After doing a few things on the base, I decided to go get Veronica. I brought her back with me and we went exploring (Looking for that damned Mister Cuddles). I ran up into one of the guard towers and the guy just starts stabbing her for no reason. She didn't react, not sure why, but we got away. Then I went to another guard tower and that guy also started stabbing her. Well, she didn't sit well with having a knife in her liver this time, so she did her little magic trick of making his head disappear.

Are you not suppose to bring a companion with you? I've started leaving her somewhere when I go there now, not wanting any of the main people to attack her and die.

What armor is she wearing?? If she is wearing some faction armor, and the guards are enemies of that faction.....

How did you get into Nellis without getting blasted??

That shouldn't be an issue. I have her wearing the power armor, but she wears that when I go into NCR territories also and nothing happens.

Luck....I was almost dead with three busted limbs when I made it to the fence...

Which power armor? There is NCR branded power armor in the game, which may be what your companion is wearing since you say NCR doesn't treat it as hostile.