So i am at Broken Oar Grotto. Serana is my follower. I just finished the quest involving the two argonian siblings (forgot their names) that get you to put out the light house, and than instead of paying you, they try to kill you. I just finished killing them.

Now, serana won't leave this dungeon. just just stands at the exit. I tried telling her "I think we should part ways" and she said she'd meet me at the fort dawnguard, and than she dissapeared. When i went to fort dawnguard she wasn't there. so i used console commands to teleport to her. lo' and behold, she's still in Broken Oar Grotto just chillin there, flickering in and out of visibility, as if she's stuck in some sort of limbo. weird stuff.

Any suggestions on how to fix this?

You can disable and enable her back. Generally this resets the characters and ai that are stuck.

There is also the command "resetai" that could help.

The best solution would be to load a save prior to entering the cave with Serana (assuming you have one). Console commands may or may not work and sometimes have unpredictable results, so make sure to save before using them as a precaution.

By the way, Broken Oar Grotto is notorious for causing followers to become stuck (possibly due to poor routing and/or navmesh problems), so I would recommend not bringing a follower into that particular location at all in the future.

You could try those too:

• If any followers remain stuck inside. It may be possible to release them by traveling to Solitude and paying off a bounty (if you have no bounty, create one). Upon release, all followers should be in your party.
• For Serana, traveling to the Castle Volkihar balcony is likely to make her appear with the Dragonborn again.
• For followers, exit the cave without dismissing or asking the follower to wait, then fast travel to Septimus Signus outpost. Wait there twenty-four hours. Fast travel back to Broken Oar Grotto. The follower will now be standing outside the cave; if they are not, fast travel somewhere and they should appear.

Load a previous save, and if you have the same problem, try those above, or as BlackPete^D say:

• Console commands may or may not work and sometimes have unpredictable results
• I would recommend not bringing a follower into that particular location at all in the future.