A companion has two lives during battle.
If the companion falls down due to lack of hp while surrounded via enemies a companion will get back up and try to help again. If the companion falls down a second time while still in combat he is dead for good.
I believe that if the companion takes a massive hit while in that crouched position they can die. I also believe that they have an increased armor rating and spell protection when they are in that crouch, so it does take a massive hit to do it.
I've had one companion die for good on me. It was that Unbroken lady who you have to brawl with in Whiterun. She's a pretty good companion based on what I've heard. Well, the first cave, pretty much the first real confrontation we hit something pretty nasty. A Falmer Gloomlurker and a Dwarven Centurion. Ms. Unbroken was dead, completely dead, before I even managed to turn around... she was hit by a double shot of that nasty Falmer poison. Based on the fact that I managed to beat both the Falmer and the Centurion, I left the poor lady dead rather than reload the save. I know when i get a very lucky win. I believe I was level 13 or so at the time.
RIP Lydia (also Skyrim complaining)
- 22/12/2011 12:37:51 AM
1041 Views
Cute 
- 22/12/2011 11:00:08 AM
730 Views
- 22/12/2011 11:00:08 AM
730 Views
Re: Cute
- 22/12/2011 11:33:54 AM
676 Views
- 22/12/2011 11:33:54 AM
676 Views
I think it is like this
- 22/12/2011 11:47:03 AM
738 Views
It's difficult to say.
- 22/12/2011 01:12:31 PM
836 Views
I thought they only died by friendly fire, but I could be mistaken. *NM*
- 22/12/2011 03:22:36 PM
322 Views
I'm currently buttering up my fellow Mage College students to get them to follow me around *NM*
- 22/12/2011 02:26:58 PM
305 Views
This is why I like to return to TES games a year later and install overhaul mods. 
*NM*
- 24/12/2011 02:00:30 PM
296 Views
*NM*
- 24/12/2011 02:00:30 PM
296 Views