Just links and prompts or summaries, as I am lazy today, but all of these fics are fabulous and you should totally read them. I love alpha/omega fics. All of these are Charles/Erik, and vary between dynamics (so for some Charles is the alpha, and for others Erik is.) While this trope has a lot of overlap with D/s ‘verses, this list is specifically alpha/beta/omega dynamic specific.
Something Primal by zimothy. Summary: Charles struggled to get out of his seat, hurrying to stand when the reality of the situation hit him. Erik Lehnsherr was his Alpha. Erik Lehnsherr was here to claim him. Erik Lehnsherr was going to do it in the middle of the classroom full of his peers.
if you wait for me, I promise you it won’t be long by asecretradio. Summary: Omega!Erik is a teacher who gets imprinted on by an alpha. The problem is that his alpha is a 16 year old student named Charles. (Oops.)
Deep Cover by Subtilior. Prompt: Omegas in heat are the perfect whores: in 5-7 days hormones make them eager whether they like it or not, their bodies are always ready for fucking, they are extremely vulnerable, and their heavy scents make them easy target. They’re extremely popular with alphas/betas who want a good fuck with an urgent edge, but not the troubles of mating/breeding.
Charles is kidnapped on his way home the first day of heat and brought to a secret location where he’s tied up in a room with his legs spread and left to service. The clients often completely disregard Charles’ cycle, fucking him when he’s over-sensitive or leaving him hard and aching.
Erik is a cop who’s been on this case for months. Finally he gets a chance to go undercover as a client. Somehow he slips into Charles’ room, which is empty because it’s the last day of heat when Charles’ about to be discharged. Erik takes one whiff, imprints on Charles and successfully breeds Charles for the last cycle. Just before Shaw and the gang bust in.
A Practice in Futility by Zimothy. Extract: In retrospect, Erik wished he’d asked Raven about Charles’ mate status before bothering to even come into the room. After hitting his 26th birthday without hide nor hair of his Alpha, Erik had come to the conclusion that his Alpha must have died before they’d ever met - leaving him unbonded and alone for the remainder of his life. Now that he was nearly 29, Erik had accepted his lack of mate in stride and continued every day without ever expecting to find his Alpha. Which was one of the reasons that he very nearly went into cardiac arrest when Charles’ brain activity spiked with consciousness and Erik’s own chest started to burn with the beginnings of imprinting.
Untitled Beta!Erik/Omega!Charles fic by anon on the X-men First Kink meme. Extract: ‘Erik,’ she begins, looking at him carefully, ‘you’re an alpha, aren’t you?’
Erik can’t reply for a long moment, shocked by the bluntness of her question. It wasn’t the first time that someone had assumed that of him but he isn’t, and has never wanted to be. He’s met a few on his travels – men who seemed perfectly rational and intelligent but who lost all ability to even think as soon as a vaguely receptive omega entered the room.
Be it Fahrenheit or Centigrade by twelve_pastels. Summary: There are very few things for which Erik is grateful. His life, his powers, the will and ability to see Shaw dead. A night in the sea with a voice in his head, and blue eyes at the surface of the water, and the words You are not alone. Primarily, however, he is deeply and profoundly grateful for not going through his first heat until he was out of the camps.
Caution - Do Not Run in Hallways by anon. Summary: Modern!AU in which freshman Charles Xavier is entering his first year in high school. On his first day of school, he runs into the tall, brooding Mr. Lehnsherr. Mr. Lehnsherr is well known among the students as a retired general for the mutant army who’s taken up teaching defense at Charles’ high school. He’s feared by all the students, mutant or human. To Charles’ surprise, Mr. Lehnsherr doesn’t
kill freak out at him for getting in his (Erik’s) way. Instead, Mr. Lehnsherr starts to act all weird, not letting Charles’ arm go, making growling/purring sounds, and acting, well, like an alpha that’s just found his/her mate. Charles promptly freaks out.
alea iacta est by anon. Summary: Underage!alpha!Erik and older omega Charles. Erik is straddling the age of majority or a little under, responsible for his age, confident, probably not a virgin. Charles is a professor who thinks of sex as an inconvenient biology thing he really doesn’t want to bother with, until Erik imprints on him in an ice cream shop or something when he’s on an outing with his friends.
All the King’s Man by Pookaseraph. Summary: Charles is an omega looking to better his lot in life by becoming a courtesan, and catches King Erik’s eye. There’s no ‘official’ summary for this so have mine: romance! hot sex! airships! politics! amazing writing and endless feels! (It’s late here and I am less than eloquent, but basically it’s fantastic.)
Untitled fill by anon. Extract: Not now. Any time, any place else would be better than here, now, and what Charles wouldn’t give to have listened to Raven and let her set up a prearranged mate years ago. It was the thing families were supposed to do for his type, but his family had always been distant at best. And every year since puberty, he’d been able to manage this easily on his own. A few telepathic nudges of “shove off, I’m mated” to the handful of alpha males he passed in the halls, a week holed up alone in his rooms with Raven for company. The cycles could at least have the grace to be consistent. He’d never gone into heat in summer before.