Raminus Polus is an imperial sorcerer and member of the Mages Guild in the Imperial City. He is the main contact for the player and by the end of the Mages Guild quest he is the only surviving member of the guild council.
When asked about a cure for vampirism he’ll direct you to Janus Hassildor the count of Skingrad who he reveals the Mages Guild is fully aware of being a vampire and that they continue a shaky relationship with Hassildor.
He also asks that you retrieve a book borrowed by Hassildor but actually is using you to spy on Hassildor to see what connections he has with necromancers that he has unknowingly working for him. After you are attacked by necromancers Hassildor will help you fight them off and chew you out for being a gullible fool and recount his shaky relationship with the guild.
When Raminus’s ice staff is stolen by the Thieves Guild because of reduced guard activity with a note from the Gray Fox himself he sends a Dremora messenger to give a complaint to Hieronymus Lex and demand he bring the guards back into the city.