How to fix (2013 update)
I've tried the bugged saved game file I initially posted in my question with the current latest versions of the official patch, Unofficial Skyrim Patch (USKP) and Skyrim Script Extender (SKSE), and the saved game is now Aspect of Peryite-free.
I've configured SKSE to use its
ClearInvalidRegistrations console command on every saved game load, which removes invalid scripts left running by uninstalled mods. This feature was introduced in v1.6.7 of SKSE:
add console command
ClearInvalidRegistrations to remove invalid
This prevents orphaned OnUpdate() events and
the resulting bloated/broken saves when removing certain mods. When
applied to an already bloated save, it will stop growing further and
instead shrink over time as the game processes all queued events. This
may take hours depending on the amount of bloat.
To execute automatically after each reload, add this to
According* to a developer of the Unofficial Skyrim Patch (USKP), the underlying cause is because DA13 ('The Only Cure' quest) is never stopped.
A possible fix* for this:
In the meantime, load an affected save, then type
stopquest DA13 into the console. That ought to put an end to that. Plus it’ll free up some unnecessarily leftover alias memory.
BTW, don’t use the console command on a save not bothered by it. Even though it may appear benign, console commands can have negative consequences you don’t know about.
If this doesn't work or if you experience issues like: NPCs not responding properly to conversation (not reply to you when you choose a certain conversation path - leaving you stuck), merchants not opening the buy/sell window, horses that can't be ridden, and other interaction issues, then the save game is most likely corrupted. Try the SKSE
ClearInvalidRegistrations console command fix I've posted above, instead.
To prevent this from happening in the PC, get the latest version of the Unofficial Skyrim Patch. This has been fixed since version 1.1 of the USKP:
"The Only Cure" (DA13) was never stopped which would lead to the Aspect of Peryite randomly initiating conversation and being unable to exit.
* This info is from the old USKP bug tracker page at 16bugs.com, which is now not viewable. The new USKP bug tracker report page of this bug is at afkmods.iguanadons.net.
In the Steam Library Downloads page, you can pause and cancel active downloads. Also by right clicking on an entry in your Steam Library, you can do the same.
Unfortunately, because steam binds this form of DLC to your account, your options are limited. As long as Steam has the DLC bound to the game, it will try to install it. You can turn off Steam's automatic updates for Skyrim, but this means that you won't get any of the updates to Skyrim and even manual updating will try to install the DLC so this is not a long-term solution. Your only real solution is to contact Steam Support and have them remove the DLC from your account.
You need to install it as you would any other game/DLC.
You can go directly to its page using any browser and click
Install Gamewhich should open up Steam and start downloading it.
After you do that, you can see it linked to the game in Steam
Alternatively, you can click
view available downloadable content for this gamefrom that last screen from inside Steam, which will take you to a page where you can also start the download, and looks like this: