There’s always debate as to what hit points actually are – to what degree hit points represent meat, or luck, or destiny; near-misses, absorbing damage on shield or armor, and so on. I like thinking of hit points as representing something different for different classes, and I describe them differently depending on which PC is taking the damage.
Since barbarians’ armor class comes from their Dexterity and Constitution, rather than armor, I picture their bodies criss-crossed by scars like Strong Belwas. (How did Strong Belwas never make it into the GoT show? He’s fire) Hit points for barbarians are them just physically absorbing minor injuries and walking through them, twisting to turn a deadly blow into a glancing one and turning to take a hit aimed at the head on the shoulder. At the end of combat, I picture barbarians as the grimiest of the PCs. For barbarians, a lot of their hit points are really just meat points.
Bards and Rogues
For bards and rogues, hit points represent near-misses, clever escapes, and glancing blows turned aside by their quickness. I’m more likely to describe a “hit” that has struck a bard or rogue as a near-miss that startles them – they feel the wind of the blade as it passes an inch from their face, that kind of thing. Only their last few hit points represent actual meat.
Clerics, Fighters and Paladins
Clerics, fighters and paladins are normally in medium or heavy armor, often carry shields, and so I see their hit points involving a lot of taking shots on their armor. An attack that is blocked by a shield can still bruise or stun the person beneath. A helm can save you from a killing blow to the head but still ring your bell or make you see stars.
Druids, maybe Rangers
Somewhere between bards and rogues on the one hand and clerics, fighters and paladins on the other, I see druids and rangers as healing deceptively quickly. They might be hit in combat, but the damage is always less than it looks. They are able to shrug off a surprising amount of injury before it begins to show. Druids will also often take damage in shapechange form and then shrug it off when they change back to humanoids, and rangers are often ranged fighters who aren’t in the midst of fights as often as other high-hit-point classes.
For monks I picture a Crouching Tiger, Hidden Dragon style fights where there is a lot of flash but weapons just happen to hand on the flat of the blade and attacks are partially deflected before they land. Often the attack that really lands solidly is the one that brings them down, since monks normally have no armor at all.
Sorcerers, Warlocks and Wizards
Unarmored like monks, and also normally far from melee combat like rangers, one would think that the arcane casters would be invariably squishy. That being said, I’ve found it’s really common for arcane casters to give themselves a high Constitution score for survive-ability. Often, Constitution is an arcane caster’s second-highest ability score. I often see arcane casters with higher hit points than druids, rogues and the like. They also often have some form of magical armor, spell armor, temporary hit points and so on, and so I tend to note that when describing hit point loss, often describing it as being absorbed by magic initially.
How do you describe hit points in your game?