Hi. Probably there's an answer for this somewhere but although I found many others with problems regarding Serana (or other followers) I did not find any exactly like mine so... Here it goes. Please bear with me for a little while...

I have Skyrim Legendery Edition, Steam account.

I "got" Serana as everyone else, when findind the first Elder Scroll.

I got through the Dawnguard questline until I met my mother-in-law... er... Serana′s mother at the Soul Cairn. Done the main quest there, released her from the barriers, got the-undead-dragon-I-cannot-remember-the-name-which-resembles-Dunhervir-or-something as a summoned ally and went back to the "real" world saving some quests completion (Arvark, and Saint Jiub's) for a later time.

When returning to Isran with the Elder Scroll I decided to go on my own again and dismissed Serana, she said she would woul be at my beck and call at Fort Dawnguard.

Many moons, and many adventures later, I decided to go finish the yet unfinished quests in the Soul Cairn, since I did forgot to use the balcony exit from Valerica's study, I had to go through the paingully long walk of Volkihar's Castle undercroft again but, this time, I decided to go alone (or so I thought, in my innocence...)

To my surprise, once I defeated those annoying skeletons at Volkihar's backdoor and as soon as I entered the undercroft I felt someone tap my back... To my surprise, there she was... Serana in all her lovely leather and black stockings... er... ok, I'll skip that part... The issue is... I'm totally stuck with her now, married for llife... I know there are a few guys out there who would love to be in this situation but, believe me, Serana all the time can be... exausting, and I I'm not refering to a ""pleasent"" kind of exaustion here , but the rather ""very annoying and irritating"" kind...

I do manage to make her wait at my home, but, randomly, from time to time, there she pops whenever I enter a new dungeon or travel to Solstheim, and If I tell her to wait at someplace, I won't have the option to get her into following me again, I just wait, go on my own, and after a while there she comes again...

When she gets into those other buggy behaviours (like running on the same place or crouching in attack position I manage to reset her to "normal" by "enable" and "disable" console commands, but theat does not resets the main problem... She is GLUED to me...

I am considering offering her to Boethia but I think that's a gruesome ending to such a lovely lass so, please, help me getting her to normal

From http://www.uesp.net/wiki/Skyrim:Serana :

Use those variables to dismiss her and then re-enable her follower package.