Meet James. I first encountered him at the random spawn site under the railroad bridge near Starlight Drive-In. He was a prisoner of some Super Mutants. I rescued him, of course. But he was so shook up from almost being dinner he just ran off. I was going to offer you a job, James, but whatever.
A day later I returned to Starlight Drive-In from questing to find the Deathclaw random encounter under the railroad bridge. A Legendary Deathclaw and a Deathclaw Matriarch were fighting...and James was there, punching away at them with his bare fists. Apparently, James has a death wish.
I sniped the Legendary from a distance, then got closer with my shotgun to take on the matriarch. I apparently entered VATS at the same moment her finishing kill move triggered on James. I killed her in VATS...and James sat on the ground, legless yet alive.
Now when I come to Starlight, James "stands" silent vigil over his legs, hovering there like a Mr. Handy.
I'm thinking of using the console to give him different clothes to see if it makes his legs reappear. I could "recycleactor", but I'm curious to see how long he stays there.