to get the vampire cure talk to any of the priests in the churches..they send you from there on a wild goose chase to finally get your cure..you gotta do alot to get ur hands on it...but once you finish it and get your cure the supplier wont have you do the same thing again if you manage to pick the disease up again she'll supply it to you then and there as far as i know..
when i got tha disease i had to go back a few saves because i had closing all tha oblivion gates by doing main missions and therefore couldnt get ingrediants in oblivion worlld
so ive learned and now im leaving both main missions and knights on nine missions last...its probably best thing to do..ive done all mage guild,fighters guild,dark brotherhood and arena quests..and now on my way through the thiefs quests..then ill probably move on to random quests in towns and then the big main missions lastly..the arena and dark bortherhood quests are my fave quests so far..the arena is in imperial city on east side of town..and dark brotherhood is easy ta find when ya get bitten by the vamp just follow his quests..pretty good..
