When the player loses health, some or all of that health with remain in the health bar, often colored red. If a player performs a certain action, such as swapping characters, that health will be recovered. Over time, red health with reduce to nothing. Subsequent hits may wipe out the previous red health, or retain a certain percent.
Bloodborne's Rally mechanic let's the player recover some health by attacking shortly after taking damage.
Torna - the Golden Country
Torna lets drivers and blades recover health by switching between each other.