Is there an in-game reason for the exclusivity of supernatural templates in the new World of Darkness? (Why can't a werewolf or a vampire awaken and be a mage as well, for example?) If there is, where do I find it?
(If I ever read such an explanation, I've completely forgotten about it.)
My view isn't explicitly stated anywhere, but I consider it supported by statements across the nWoD books. There are a few representative quotes from the core books I own at the bottom.
To do anything majorly supernatural, you need to be more than human. A vampire's soul is deadened and blended with the Beast from his sire's vitae. Werewolves are born with a soul that is supernaturally potent but sleeping for years. Mages awaken and gain sympathy between their souls and the Realms Supernal. Changelings are torn, mangled and blended with Fae stuff.
None of these changes can coexist in one person. Taking a Mage for an example. If you aren't a normal mortal, then you cannot be in close enough sympathy with the supernal realms to perform magic.
From Vampire The Requiem 181
The change from life to undeath affects more than a person's body. It changes the soul.
From Werewolf the Forsaken Page 75
A werewolf is born supernatural, with the soul of an ancient predator.
From Mage the Awakening Page 32
A mage who loses his soul immediately enters Sleep until it is restored. His ability to perform magic is gone. If the mage somehow gets his soul back, he needs a full night's sleep before he can use magic again.
From Changeling the Lost Page 24
When humans enter the Hedge, the Thorns do more than tear at their flesh — the Thorns rip away at their souls as well.
and
While the human soul is not quantifiable, there is a certain something which makes humanity humanity, and it is this same unique characteristic that begins to unravel like a mis-kint sweater the deeper one travels into Fae lands.
The in-game reason appears to be “It just doesn't work.”
Vampire: the Requiem, page 168
Kindred Vitae, while potent, does have its limits. When the other supernatural creatures with whom the Damned occasionally cross paths come into play, certain realities of the World of Darkness supersede the mystic strength of the Blood.
Werewolves and mages are immune to the Embrace. If a vampire is somehow able to extract all the blood from a werewolf or mage and attempt the Embrace, that Embrace fails automatically.
Mage: the Awakening, page 65Note that a character cannot possess multiple supernatural templates... A vampire or werewolf cannot Awaken...
I suspect it doesn't work by design because they wanted to avoid the mixing madness of classic World of Darkness.
The reason is that the nWOD system just doesn't allow for it. It works off of a standardized core book for all the lines; World of Darkness Rulebook.
oWOD doesn't do this and essentially has the various game lines such as Werewolf: The Apocalypse and Vampire: The Masquerade that can be mixed, but are essentially worlds unto themselves. For example; In that world there are such things as Abominations. A Vampire Werewolf hybrid. These are Embraced Werewolves that both possess the power of Gnosis an Kindred Vitae. But even the books never state that those werewolves are the same ones in both worlds. The writer of the VTM translation guide for oWOD to nWOD even specifically makes this point:
But in the original World of Darkness, the different game lines were ostensibly worlds unto themselves. That is, although crossover systems and products existed, it was always stated up front that the 'Lupines' of Vampire: The Masquerade weren’t necessarily the Garou of Werewolf: The Apocalypse. In Requiem, this isn’t true. The core rules of the setting are found in the World of Darkness Rulebook
I'm not saying that you can't do this for nWOD, it will just take some very creative leeway with the defined set of rules. But in the end, even White-Wolf states that all the rules in the book are nothing more than suggestions and that you should have fun with it.
White Wolf has always tried to be apart from munchkinism or combo practices so common in other games. So, with the exception of the oWoD's abomination, and maybe some ghouls, every time they introduced a supernatural type, they made imposible to combo with another.
They knew that a lot of players would try to take advantage mixing two (or more) supernatural types. So, they allowed no one, even if sometimes the mix sounded more plausible and logical than the explanation of why it didn't work.
Think of playing vampire with a group of one vampire-mage, one vampire-werewolf-changeling and one vampire-mummy. It's munchkin and it's ugly.
