Sounds good. I'm a Changeling fan primarily but I'm very much into crossovers. Given how much Vampire history affects human history and vice versa and how spotty Fae record keeping is, that totally makes sense.
The idea of playing Changeling underdogs in a mostly Vampire world sounds amazing, so I look forward to the Holy Fury updates.
The Holy Fury update is live. You can download it here from the forum or from ModDB. It will be live on Steam just as soon as the uploader in CK2 functions correctly and uploads the mod.
For Fae/Changeling, the following features are implemented:
A distinction between First Born Fae and Changeling characters (by traits). First Born Fae and Changelings can reproduce through breeding. If they breed with a human, the offspring have a change to be changelings but are otherwise Kinain. Any Kinain has a rare chance to breed a changeling.
Arts and Realms exist as traits that offer passive bonuses.
Glamour can be used to heal wounds and a handful of other supernatural abilities. Glamour in a similar mechanic to vampire's using blood. Glamour increases slowly over time, but you can ravage a dreamer for a quick increase.
Trolls, Sluagh and Red Caps have custom character portraits. Sometimes, even their Kinain descendants inherit if not the powers of a full changeling.
The Seaonal Courts exist as Religions in 1215, while in 1350 the commoner Changelings are divided by Seelie and Unseelie faiths.
At the 1215 bookmark, the Sidhe have 13 noble houses that function as dynasties with the canon coats of arms.
It is possible that a Fae or Changeling can be successfully embraced into vampirism, though there is a low chance of success.
It is possible to create a First Born Fae or Changeling ruler in the Ruler Designer.
First Born Fae and Changelings kiths tend to be generated in geographical areas that make sense for their Kith: Trolls in Scandinavia, Red Caps in Scotland, Sidhe in Ireland, etc...
There are a couple of artifacts specifically for Fae/Changelings.
There are Fae/Changeling Special Troops type, and those troop types make use of underused Paradox models with the POD Units submod.
Here is the dynaically generated Shattered World map for the 2015 bookmark showing the various season: