In the Darkfall passage there is a bug where if you tell Serena to "wait here" you do not have the option to tell her to "come on" or "come with me"... I am on Xbox BTW.

This just happened to me now that I am pretty deep into the passage and unfortunately my last save is at the very beginning... hate when I do that.

My question is, If I just leave her behind will she eventually load up towards the end of that quest, where we fight the dude with Auriel's Bow and she is needed to finish the quest, or do I really have to start from the beginning?

I'd start from the beginning. Best to cut your losses now.

You'll need her with you before you fight for the bow - she's needed for a cutscene that has to run before you can even get to Forgotten Vale.

If you get to that point and she doesn't catch up, you're probably going to have to replay the entire dungeon.

That's part of the reason why I never use her as a follower once I finish Dawnguard. She's too buggy and glitchy to be worth the bother, even on PC with the console to help you out.

I would have to disagree. I've had hundreds of hours of gameplay with her and I've encountered no problems. I'm on PS3 too.

I am just going to start from the beginning and cut my losses now, like Person12321 said. I am not going to just go further if there is a chance that she will not come back.

I also cannot stand having followers, no matter who they are, because they totally kill my playstyle which is almost always stealthy. I Just don't have a choice when doing this questline, obviously.

Thanks

Well, my experience has been very different. She gets stuck in terrain, stuck in animations, gets separated from her horse and her AI glitches out, sometimes won't heal after a big battle and she's on the ground, ...

I'm on the PC - it may be mod issues with my game.

Your Serena has a horse? mod I assume?

I have actually not had any issues with Serena except this. The reason why cannot stand having her and others as followers is that they attack the moment something or someone aggros.... it drives me insane. There is the occasional lag behind and permanent sneaking crouch issue but that doesn't kill my game or anything.

Convenient Horses - she summons a spectral horse, like Aarvak, that runs up to enemies and explodes. You can make her ride a normal horse, though.

My current character is my last character on Xbox, I will be going to PC very soon. Can't wait for the mods. I actually have the capability to do it now, I have a new GPU and RAM sitting here waiting to be installed, but I am actually enjoying my current character and I don't want to quit him yet.

Have fun with him. Hopefully Serana behaves properly when you clear Darkfall Cave again.

I am also on xbox and have had the same problem. Had to load a previous save.