I love the letters sent by the hirelings with crafting component shipments. The stories are amusing and it adds a sense of depth to the world. Why not utilize this for PVP as well?
The Vestige cannot be killed. For some reason the main quest never really explains how this is possible and yet other characters in the game world are aware of the Vestige's unique condition. I would have loved to hear a theory from Tharn concerning the Vestige's astounding ability to harness raw creatia and regain corporeal form or to listen to the Prophet speculate on divine metaphysics. Regardless, any alliance would highly value an immortal soldier. As the Vestige increases their PVP rank they should receive letters from military officers and political leaders of their alliance that reflect their rising status. Civilians, possibly quest NPCs you have assisted in your travels, could send you letters of encouragement and support. Citizens of Cyrodiil could send you angry letters about the collateral damage and innocent deaths to better reflect the reality of war. Perhaps NPC soldiers with whom the Vestige could interact and develop a friendship or rivalry could be added to the home camps of each alliance and the Vestige could receive letters from them about their experiences. Perhaps some could occasionally die to help inflict a sense of loss.
I think it would really flesh out the story of a large and mostly empty zone. Thoughts?