[@DoomFlavored]The Sith Empire doesn't have trained Force users.  There are instinctive dark side Force users, many of them in the Sith Empire, so you could be the apprentice of one of them, which the Jedi take in after your master is defeated.  Maul and Dooku are possible candidates for Master, as they will likely die at some point.  They wouldn't tell you the identity of their Master, outside of calling him "Darth Sideous" (who is an agent for the Sith), but the Jedi would know that he exists.

[@Pyromaniacwolf]Sounds like a good start.