Oh, there is so much myth to dive into when looking for a sponsor! I've had so much fun reading back over some of my old textbooks looking for inspiration (I studied ancient history in college). Here's an example that I used for an NPC character of mine (forgive the backstory, but it sets up the Sponsor):
Mario Martello, patriarch of the Martello family of Sacramento, originally hailed from Eastern Italy before immigrating to the United States with his family in 1937. He enlisted in the Army following Pearl Harbor, and qualified for training with the Devil's Brigade, the American-Canadian 1st Special Services Force (and one of the grandfather units of modern US Special Forces). Sergeant Bosso (as he was then known) was among the first soldiers to land in Italy, and was commended for his valor in combat. Mario was greatly troubled by fighting with his fellow countrymen, but knew that Italy was on the wrong moral and ethical side of the Second World War.
Scouting along the countryside one night outside of Anzio, Mario came across three wounded and starving Italian soldiers. Martello administered medical aid to the best of his ability and offered the three men some of his own rations before claiming them as prisoners of war. The next night, again on a scouting patrol, Mario was visited by Diomedes, the former King of Argos and hero of the Trojan War who was elevated to Godhood by Athena for his deeds in the Trojan War and the service of his late father, Tyedus.
Diomedes was an ideal soldier, one who treated his enemies with respect but also showed no fear in combat. Diomedes and Herakles are unique among myth for being the only mortals to wound members of the Pantheon, though Diomedes is especially noteworthy given his lack of divine birth. He was respected for his wise counsel, and was among the most wise of the Greek leaders despite his relatively young age (though, admittedly, he was the most distinguished veteran of the Epigoni War). Following the destruction of Troy and the fleeing of the Trojan people to Italy, Diomedes himself left Argos and migrated to Italy, where he founded the 10 Italian cities. Fans of Virgil will remember his famous appearance in the Aeneid.
So, to make a long story short, Diomedes recognized several very important traits in the young solider, and offered him an opportunity to make a difference in the world. As a God of Heroes, Diomedes has spent countless generations empowering a mortal to serve as his Liaison in the mundane world, working to keep average people safe from threats they don't understand. While his power has diminished significantly from what it once was, Diomedes none-the-less lives on in history and literature classes around the world.
Being Diomedes' Hammer (Italian translation: Martello) is a thankless job, one filled with restless dreams and a hyper-awareness that forever destroys one's opportunity to live a normal, quite life. In return, however, Mario was granted the skills of Diomedes himself, among them excellent prowess in combat, uncanny wisdom, and the ability to quickly recover from injury. Since taking on the mantel of Martello sixty six years ago, three generations of Mario's family have fought tirelessly to make the world a slightly safer place to live...regardless of the cost.
