Imagine characters functionality like attach, defend, eat, join group, fear.
For example Bob can attack and join group, John can defend and eat, and Kate can join group and fear.
But all of them can share this functionality by bite each other and share some functionality. Like if Bob bite Kate, Kate gonna addiotionaly do an attack. It all just like natural breading works but much faster through biting, that suitable for games.
We gone setup this functionality just like gens with dominant and recessive gens. So functionality of NPC will be stetted by some kind of DNA that can change during gameplay.