Final answer:
Gawain gives back the game he obtained during the hunt to Bertilak and his lady as part of their agreement and as a gesture of courtesy and gratitude.
Step-by-step explanation:
When Gawain returns from the hunt in Sir Gawain and the Green Knight, he gives back all the game that he has obtained to Bertilak and Bertilak's lady. This is because Gawain is staying at Bertilak's castle and it is part of the rules of their agreement that they exchange what they gain during the day. Gawain gives the game willingly as a show of courtesy and gratitude for hosting him.