What is the connection between the Shadowfell and Strahd/the plane of Barovia?

Question

I'm preparing to run Curse of Strahd, and one of my players wants to play as a Shadar-kai who is loyal to the Raven Queen.

In the adventure's set up, it says (p. 9):

Unwilling to go the way of his father, Strahd studied magic and forged a pact with the Dark Powers of the Shadowfell in return for the promise of immortality.

For obvious reasons, I'd like to know more about the connection between these Dark Powers of the Shadowfell and Strahd.

I've looked at the related question What are the "Dark Powers"? but it seems to be an old question based on old D&D lore (from 2e and 3e) that doesn't help in this regard, because the Shadowfell appears to have been introduced in 4e (and remains in 5e). Hence this question about the 5e adventure Curse of Strahd and the 4e/5e Shadowfell is not a duplicate of that question.

Rather than focusing on the Dark Powers (since that would make this a duplicate), I want to instead better understand the relationship between Strahd, Barovia and the Shadowfell, especially if the Raven Queen is supposed to be in any way related to any of this. If it turns out that she is related to this, then this player's backstory will have to include why the Raven Queen is sending their PC to ruin Strahd's day (especially since, AFAIK, the Raven Queen dislikes sentient undead), whereas otherwise the "Raven Queen dislikes sentient undead" thing is probably enough on its own.

So, in what way is the Shadowfell related to Strahd, and the plane of Barovia (if at all)?

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I'm chiefly interested in any 5e lore that might help me understand the connections between the Shadowfell and Barovia/Strahd, but 4e lore is acceptable as well. 3e and older lore I won't shun if it can help in any way, but the fact that the Shadowfell didn't exist back then implies that answers must contain at least some 4e/5e lore as well for such answers to be helpful.

Answer 1

The Domains of Dread are in the Shadowfell

The plane of Barovia is a Domain of Dread, and Domains of Dread are located physically in the Shadowfell, in a far remote corner of the plane and hidden away from the rest of the Shadowfell. (DMG 51–52)

The Raven Queen is also located in the Shadowfell, where she controls several domains, but that is where the similarities end. She is not related to Strahd in any way and isn't mentioned in the campaign at all.

If the Shadowfell is planet Earth, then the Raven Queen owns some land in Russia and Strahd lives in Brazil and you are looking for a connection between the two. The connection doesn't really go much deeper than "they're on the same plane". The Raven Queen has no power over Barovia and most likely doesn't even know much more than "it exists", because information and people do not leave the Domains of Dread very often.

Residents of the Shadowfell have no easier a time entering or leaving Barovia than normal residents of the material plan do. In fact, there are multiple Domains of Dread, where others are trapped just like Strahd is, and even those Domains of Dread will have little to no interaction with one-another. They are essentially mini-planes with hardly any way of entering or leaving.

Answer 2

The Shadowfell is the plane of darkness. It has an ambient, low light and does not have any stars or moons that would grant light otherwise making the entire plane a grayish hue lacking vibrant color.

The plane itself pre-dates 4e and 5e, and has mostly remain unchanged since its introduction in Dragon magazine in 1995, just more fleshed out since then. This would have been near the end of 2e's lifecycle, with 3e coming out two years later.

Several demiplanes exist within the Shadowfell, and one such plane is the Domain of Dread, also called Ravenloft. In this sense, a demiplane is a small slice of the larger plane that can function either connected or not connected to the larger plane as the story demands.

Barovia is one of the locations within Ravenloft in 4e and 5e, though is previous editions was its own distinct world. Strahd is the Baron of Barovia, and in Curse of Strahd he is able to control the mists that allow or prevent entry at will, which separates Barovia from the rest of the worlds.

So to summarize, Shadowfell is a plane of existence. Ravenloft is a slice of that plane. Barovia is a region located in Ravenloft. Strahd rules Barovia.

Answer 3

According to the now available book "Van Richten's guide to Ravenloft" in a section about the goddess of the mist "Ezra" there is a vague mentioning that this could be the Ravenqueen herself.

The Ravenqueen has always been mysterious in the way she operates she might work under many names that we might not know yet. It would make sense for her to be one of the Dark Powers, since she (at least in 4th edition) was mentioned as the Power with the most influence in the Shadowfell. It is also mentioned that the Dark Powers don't have to be evil.

It is also mentioned how a Domain of Dread is formed and that is by someone committing such a horrible act that this "negative act" sucks them and their surroundings into the Shadowfell where they are isolated by the mist. In my opinion this seems to be a countermeasure of the Gods when something very evil appears on the material plane that can't be dealt with in time without causing too much casualties. Therefore the gods just cut out this "Area and the creature that committed this crime" (kind of like a tumor that is removed before it can effect the whole land.

Spoiler for CoS ahead: In the case of Barovia and Strahd: The Evil pact that was fulfilled by Strahd killing his own brother and Tatyana jumping to her death. This let loose to the Evil powers of the vestiges (Vampyr) or whatever you want to call it in your campaign. It was such a great thread to the lands surrounding old Barovia that it was immediately sucked into the Shadowfell.

I could imagine good Gods having a pact with the Ravenqueen for these kind of scenarios. Because both sides gain something from it. the Shadowfell is like a Junkjard for the good gods where they expose evil.For the Ravenqueen however, who collects evil memories/artifacts and souls there is a lot of evil power that she could use for herself. (especially because she hates undead. Vampyr could be under Vecna or Orcus'es rule)

But overthrowing these domains is very difficult for the Ravenqueen herself, because the mist-spell is so potent to contain the evil within. That she needs lots of preparations to overthrow the Darklord and make sure the Vestigaes/Ampertempel/Evil is contained. In the CoS adventure I dm'ed the WereRavens, the Dusk Elfs and even the Vistani were to some extend followers of the Ravenqueen, that infiltrated Barovia in her name over the years. The Dusk Elfs look identical to the Shadarkai and the WereRavens probably gained their powers from the Ravenqueen herself. Madam Evas powers were also gained by the RQ in my campaign. (RQ in 4th edition had the portfolio of Fate which would make sense for her to grant Madam Eva "Fate" powers)

After CoS the players were able to defeat the dark Lord and were then instructed by the RQ to seal the Amber temple and how to open a portal to the Shadowfell so her armies of Shadarkai could conquer Barovia an cleans the land. (she also included it to her Domain and never returned it to its original place ;D) The RQ was of course very generous to them since she has many artefacts and lots of knowledge about the universe which the players to gain.

It gives a good ending to CoS and makes sense. Only thing to discover is which good gods might be part of the Dark Powers any suggestions?