Tiefling In My Greyhawk Campaign;

I am an old Grognard, having played "D&D" since it was a three-book set called "Chainmail", and IMO Greyhawk is the best and only campaign setting. So, when updating to 5e I had the issue of Tiefling and Dragonborn to wrestle with. I find the "they would be considered monsters and immediately murdered" argument to be lazy and unimaginative. I made Tiefling a bloodcurse on the Suel race. Short version is that before Glasya got tied down in Malbolge she made a visit to Oerth and had a tryst with a pre-Invoked Devastation princeling. He ended up "breaking her heart", which roughly translates as he found a way out of his contract with her before she could collect. She honored her end as it was written, giving him power and position, but in revenge she placed a curse on his line and gave him the libido to spread it. Generations later the first Tiefling appeared. The Suel mania about bloodline purity stems in no small part from an attempt to remove this "blight on their people", but as Tiefling are only born into "pure Suel" bloodlines this program is actually working against them.

As a general rule Tiefling are not born, they become. Think Marvel mutants and hormones. The extremely rare one that is born does not last long, owing to either being left out in the elements to die of exposure, or simply getting murdered outright. When the transformation occurs later in life varies widely, with those happening early being abandoned or sold into slavery, and those happening later on committing suicide or running away. Most Tiefling come from the Scarlet Brotherhood, and having one born into your family will get the mother removed from the breeding program there. Once again this actually works against them as the curse is carried by the father.

Tiefling cannot have children with another Tiefling, nor with orcs or elves. Children born of Tiefling and non-Suel parentage are always human, and either male or female can create a Tiefling (roughly 20% chance) if their partner is pure-Suel. Tiefling are exceptionally rare, and nearly all of them are adventuring classes of some type. There is a small enclave of a dozen or so living in Greyhawk, most large cities outside of Suel control have one individual living freely there, and there is rumored to be a village in the Hellfurnaces where a couple dozen live in seclusion with their families. Any Tiefling still trapped inside the Scarlet Brotherhood lands are prisoners, slaves, or worse. Suspicion and fear are the usual reaction they will get no matter where they live outside the enclave. Lets be honest though. In a world where a dragon can swoop in and devour your village, actual demons pop up occasionally to steal your sons and daughters, and even gods have been known to walk Oerth, seeing a humanoid with dark skin and horns is hardly “the strangest thing I saw this week”.

In the interim Glasya has gone from aggrieved to deeply amused and plotting. As with everything among the infernal she is now figuring out how to turn this to her advantage. She knows that when she finally moves on her father’s throne she will need an army, and a large cohort of battle hardened and adventurous “children” could be the game changing power play she needs. When she calls them they will have to answer, and even the most noble and good among them are still doomed. Tiefling found on other Prime Planes are the result of Glasya expanding the program, or adventurers plane traveling there and remaining. How making more Tiefling on other planes works is to be determined later.

I would be happy to share my thoughts on "Dragonborn in Greyhawk" I would be happy to share those as well. Keep in mind that this is how I handle it in my campaign, it violates several tomes worth of canon, and I personally don't care.