Hi there throwaway825901, I'm glad to hear that you are finding Scarleteen a valuable source of accurate information about sex and sexuality. Let me start by saying that reading erotica and engaging with sexual media in general is nothing to be ashamed of, however we understand that there are still unhelpful cultural messages about sex and shame that are still around that can be difficult to grapple with. If you'd like to read a bit more about this, we have a great article about it here:
undoing sexual shame.
I would be remiss though if I didn't also include a gentle reminder that as you are 17, to be aware of the age limits in the user guidelines of the websites you are using to access sexual media, as this indicates the audience that the website are expecting are reading their content, if they are 18+, they will not be considering the appropriateness/safety/assumed knowledge around sex of younger viewers for this content.
These articles are really useful for informing your reading/viewing of this kind of media (they primarily refer to video content in the title but many of the principles apply to written sexual media as well):
So, what is "knotting"? It is actually a fan-fiction specific and actually fictional sexual practice (which is not actually achievable with human penis anatomy), essentially it imagines that the character(s) with penis(es) with canine (eg. Wolf) characteristics. To explain without getting too deep into the biology: canines have penises but like many mammals, they have physiological differences from the penises of other mammals. One canine feature is that when a canine penis is erect they get a bulb on the end (the "knot") that "locks" into a corresponding location in female wolf's vaginal canal until intercourse in complete. In many of these works of fiction, the fantasy anatomy often also imagines a receptive male partner's anus as also having the corresponding anatomy for the penis to "lock" into.
Fanfiction has many tropes that are largely unique to it as a genre of writing (eg. AU fics, the term "slash" etc), and it has subtropes specific to erotic fanfic as well. Creating erotic/relationship scenarios that engage in fantasies around power play (submissiveness and dominance) structures, centred around wolf pack dynamics of "alpha", "beta" etc. (which actually are a myth and don't exist in the wild) are a more niche subgenre, but are used across fandoms so it is not surprising that you've come across some, and from my reading, some of these tropes have extended into this trope of "knotting", in a manner that is extending the sub/dom metaphor.
Earlier on I mentioned the article about reality checking sexual media, this trope is a good example of why it is important to consider the specific context in which a piece of sexual media exists, and that it is always fiction and fantasy. "Knotting" is a particularly useful example because it is
so fictional that the sex act itself is not possible in real life, along with that, the kinds of dynamics it portrays between the characters in terms of sub-dom relationships, and emotional/physical safety and consent may not reflect what is safe, right or best practice in real life (and would be sexual assault in real life), because it is fantasy and the characters aren't real people who have emotional or physical lives outside of the story, does that make sense? This doesn't mean that they are "bad" to read, however it is important to remember that erotic content is fantasy created for entertainment, and often should not/cannot be reenacted in terms of script/or the sexual acts depicted.
I hope you found this answer useful! If you have any further questions, curiosities or observations that you feel comfortable sharing, please don't hesitate to add them in a reply below.