Basically, a fight is a physical contest of wills. Yes, injuries are a big part of that, but when you break it down, having one's shoulder dislocated, or being blinded by a cut over your eye -- it all works to break down your willingness to continue fighting. It's never a logical, rational thought process -- "Well, I've taken approximately 70% of the damage I can withstand, so I should stop now. And that's how I see HP. It's your willingness to keep recieving and delivering punishment, and while that is related to injury, it is independent of it. From a game perspective, once your HP reaches Zero, your character is simply done -- they've given up, even if it is involuntary.
And this plays true IRL, too. Someone gets in over their head, and loses a fight, they can nurse a grudge and feel like they "shouldn't have" lost. They can feel like there was something external to blame, and blame that ("he only won because he got the drop on me"). In the end, the results are still the same: a person loses a fight because they ran out of reasons to keep fighting.
The reverse can also hold true -- there are countless war stories where someone charged a hill, and was riddled with bullets, but didn't stop until they had completed their objective. They ran across a battlefield carrying a wounded friend, or charged up a hill to lob a grenade into a machine-gun nest, etc. The list of examples is endless. Again, the result is the same: They "won" because they didn't lose their morale. They might have even died as a result of their wounds, but even mortally wounded, they kept going because, in their mind, they weren't done yet.
Maecius wrote:Back when I played actively, I'd usually just shoot the player in question a tell. "Is your guy visibly injured?" If yes, react appropriately. If no, ignore the fact that they haven't hit the R key yet.
A little bit of courtesy and communication goes a long way in establishing a collaboratively storyline, even with some "random character" you haven't met before. Could be your character's next best friend, after all! Especially if they do say they're injured and you patch 'em up or toss a potion their way!
This is what I try to do, also, while keeping in-game, such as: "You look a mess! What happened?", or "You look fatigued..." which puts the level of visible injury squarely in their court.