1. BOS or other guy gives you quest to go into glow and use the computer down there. If you die then you lose the quest and can retake it after a timeout. If you succeed in using glow computer and getting out alive then you get reward from the quest giver.
2. San fran tells you to escort scientist to vault 15 computer, he becomes your companion and your mission is to keep him alive.
3. Raiders give you flare to set up trap for players and you must survive 10 minutes in the flare trap to get reward.
This is an example of pvp quest where the mission is to not die inside a pvp territory. It creates a meaning to death = you lose quest and get no reward.