Additive animation
Add the difference between two poses on top of a running animation instead of blending between whole poses.
Ordinary blending picks a mix of finished poses. Additive animation does something else: it takes the difference between a clip and a reference pose and adds only that difference on top of whatever the character is already doing. An aim sway, a recoil kick or a breath can go on while the figure runs, without overwriting the run cycle.
The trick lives or dies on the reference pose. Get it wrong and the addition starts from the wrong place and the limbs drift. Used right, it's the backbone of how modern games stack many small motions — lean, hit reaction, fatigue — on top of a handful of base loops.