Right I wanna know too!
It's like some kind of trick so the alpha can be sure that the Omega is pregnant when there done or something like that
when an alphas (this happens to dogs too) penis, specifically the bottom or "hilt" swells up making it impossible to pull out to ensure proper insemination.
Example in a manga
http://www.mangago.zone/read-manga/boku_no_high_spec_kareshi_sama/raw/mi-chapter-5/pg-29/
Imagine something similar to like animals knotting during intercourse (i.e. dogs). Makes it so they literally can't pull out ╮(￣▽￣)╭
In Omegaverse Alphas have a knot at the base of the penis. It pretty much holds it inside the other and won’t be able to be removed until they’re released everything inside their partner and most of the time almost guarantees pregnancy in Omegas since Alphas have a higher sperm Count. So it could last 20-30 minutes.
The more you know
I see! Thank you all
Whats knotting tho?