Here is another approach, tell us what you want to play. Detail him story wise as much as you can and we can help you, tell you different ideas to get what you want.
Fair enough.
I have a couple of ideas and was hoping to glean some incite from how they've been shown in the books before settling on one specific idea.
I was thinking of playing a guardian angel.
After thinking about it for a while I thought that it might be more fun to play a human who was assigned Guardian status by an angel. My thought was that Guardian Angels are not always angels but human representitives who are given abilities and items of power to act as Guardians on earth for the Heavens.
Another thought was that my character would not technically be a guardian angel but carried an item that was imbued with the soul of an angel (or a protective spirit (ala Bob) that would supply the powers and abilities for my human host character.