There are a lot of things that will turn me, instantly, off of a story, and for years Mpreg has been one of them. I hate it. I hate the way it makes women unnecessary. I hate the plot gymnastics necessary to accomplish it. I hate the requisite hormonal crying/eating ice cream and pickles or whatever other one-dimensional pregnancy cliche the author will feel it necessary to insert. I hate it in a house, I hate it with a mouse, I hate it here or there, I hate it everywhere.
Except... I found a time I did not hate it recently. In the Omegaverse.
I'm told by Fanlore that I can blame Supernatural for all of the A/B/O strangeness that has flooded some sections of AO3, but in some ways, I think that the real blame can be placed with these guys.
(If you think Pon Farr isn't the origin of the whole 'sex pollen' trope as well, I have bad news for you.)
It's not impossible for me to see the appeal of some aspects of the concept of a sex emergency. It just often necessitates a certain level of dubious consent, which is obviously problematic; and A/B/O dynamics in particular have a lot of potentially misogynistic elements as well. (Let's not even get into anatomical issues inherent in most Omegaverse stories, that's a whole other kettle of fish.) These are all things that can be negotiated by a skillful writer who is willing to take the time to subvert the trope, of course, but that requires a level of time and effort that not everyone will be willing to spend on their porn.
That's the catch, though-- it is, almost exclusively, porn, and if you, like me, are sometimes looking for something a bit NC-17, chances are, you've run into a fic or two tagged things like 'healing cock' and 'Fuck or Die' that, once clicked on, was revealed as some of that weird knotting dick porn everyone's been warning you about.
If, once you clicked that link, you found yourself oddly fascinated, I have a suggestion for you.
You were kindness when I was a stranger was my gateway drug, and is (obviously) not safe for work. Without previous A/B/O experience, I initially found it to be a little confusing, but I think anyone familiar with the precepts will have very little difficulty enjoying what was some of the best erotica I've found on AO3. In fact, I'd suggest exploring the rest of suzukiblu's fic, with the caveat that many are WIPs, for those who enjoy this sort of thing.