I'm trying to play Dawnguard and Serana won't speak to me until I get rid of my 'interloper.'

Problem is, I'm playing this week for the first time in maybe 10 months and have no idea who this interloper might be. I've tried waiting 3 days (tried 8 actually). I've tried getting married to see if they'd show up at the wedding... I have no idea who this person is or where to find them and I'd rather not spend the next few days wandering around random bars to try to be able to play the DLC I bought.

Any ideas???

Thanks in advance.

I wish they had a Companion Dismissal Terminal in this game. Since you are on a console, you either have to load an earlier save from before you lost the follower or you can try waiting in cell for 11 days or 31 days, as those are the reset timers for most any script out there (you already passed the 73 hour one)

I don't know if you have done the Companions quests on your current game or not, but there are several instances where the game should force one of them to accompany you, which should "dismiss" the follower that is causing the issue. Here is a list of quests that should force a follower reset:

Main questline (one-time quests)

http://www.uesp.net/wiki/Skyrim:Proving_Honor

http://www.uesp.net/wiki/Skyrim:The_Silver_Hand

http://www.uesp.net/wiki/Skyrim:Purity_of_Revenge

Side quests

http://www.uesp.net/wiki/Skyrim:Purity (x2)

http://www.uesp.net/wiki/Skyrim:Totems_of_Hircine (x3)

Radiant quest(s)

http://www.uesp.net/wiki/Skyrim:Dragon_Seekers (radiant/randomly offered) -- can only be offered by Farkas and Vilkas and only if you have completed both http://www.uesp.net/wiki/Skyrim:Glory_of_the_Dead and http://www.uesp.net/wiki/Skyrim:Dragon_Rising.

I've already done pretty much all the main storylines, including the companions. But I went back and talked to Farkas and he had a dragon that needed slaying and once I accepted that, it said my companion has replaced my follower. After killing the dragon, Serana was willing to talk to me again. So, that worked.

Thanks!!!!!

You're welcome. Good to hear that it actually worked!