So I was in dialogue with someone and while they were speaking, Serana lays on the floor as if shivering XD I'm just sitting there laughing and thinking what the hell is this woman doing. Does anyone know what she is doing, and has it happened to you before?

Also, I was talking to Teldryn Sero, and he told me the story of his previous companion who died trying to take on a whole fort of bandits near Whiterun. Teldryn says that it was the greatest bandit camp he has ever seen. Anyone know which camp/fort he's talking about?

Not sure about Serana but the fort sounds like fort Greymoor to me....it's a pretty challenging bandit fort to the west...there is another large bandit fort in the mountains on the road to the reach as well!

They gave her some extra animations to give her some life, she seems to be Bethesda's response to the common complaint of how lifeless a lot of NPCs felt in Oblivion and Skyrim. She's not perfect, but I definitely think it's a step in the right direction.

Because of this, she interacts with things that other NPCs can interact with. She'll work forges and grindstones and whatnot if you stand still long enough. That's why you'll sometimes catch her leaning on a fence or a wall that some other NPCs lean on. She's coded to follow EVERY animation though, so that means she'll do things like pray at High Hrothgar, cower in from of Molag Bal's shrine in Markarth, etc. I noticed in that dwarven ruin involved in the College of Winterhold questline, there's that mage that's laying in pain on the floor at the entrance. After he died, Serana took her place in the same pained position until I moved.

So short version, it's a side effect of Bethesda's attempts to make her a little more lively than other people.