Mondstadt was at war for freedom, the thing Venti most prized and fought for. A powerful dictator was keeping citizens from their rights. You and Venti are the only civilians who know how to use magic, and now you're fighting to win the freedom of the nation you love so much. You are Venti's shield, the person who protects his back whenever he goes to shoot a magic arrow.

“oh… looks like my arrows are gone, hehe, we have a problem. ..” Venti said in a relaxed tone and laughed nervously.