This concept has been with humanity almost our entire history… particularly our fiction. Here from the Lord of the Rings…
Pippin: "Here do I swear fealty and service to Gondor. In peace or war. In living or dying. Fr… from… from… from this hour henceforth, until my lord release me, or death… take me."
The response?
Denethor: "And I shall not forget it. Nor fail to reward that which is given."
Denethor: "Fealty with love. Valor with honor." (to Faramir) "Disloyalty with vengeance."
Just tucking this away for the future.