As someone who was unfortunate enough to find omegaverse fics filled with gross stuff over the years (you know, romantization and glorification of s3xu4l 4ss4ult and/or r4p3, toxic/violent relationships, fetishization/infantilization of omegas, etc) I think that one interesting topic that could be adressed in omegaverse AUs/stories is the oversexualization of Young alphas/omegas and the normalization of predatory behaviors as a consequence
Even thought this usually varies depending on the author's choices, many versions of the ABOverse agree that alphas/omegas start developing their secondary sexes during puberty. Usually alphas get taller, more muscular and "mature-looking", while omegas are small and frail, which gives them an innocent and cute appareance. Those traits are ABO society's beauty standarts in most versions of the genre, and at the same time they are very sexualized and fetishized on fics. However, Its never adressed how those sexualized beauty standarts would realistically affect the individuals, who in most of those stories are in the age range of teen-young adults.
Just imagine that youre a teenage omega, your short stature, frail-looking body and your soft fatial features makes It very evident. Everytime you walk throught the street you see not only Young, but full grown alphas that could easily be your parents getting flustered at you, making gross comments about how "perfect, innocent and cute" you are or about how you should belong to them and be their spouse, and some of them even talk about taking you by force someday. All your social media accounts are anonymus because otherwise you get harrased by Alpha users. It has reached a point where you cannot leave the house unaccompained due how scared you are. Why are all those alphas so creepy to you? You're just a kid!
Now lets imagine that youre an Alpha teenage: Suddendly everyone treats you like an adult. They seem to forget that just because you look like one doesnt mean that you are. Many family members start talking weird about you, saying that you're ready to be a leader, to marry and breed with omegas and "dominate them" as any Alpha should. You have also encountered some omegas telling you that you are very hot, muscular and such and they want you to bite them, they don't really leave you alone till you tell them that you are 15. When you tell your loved ones about it they don't care very much, after all, you are already an Alpha, you should feel Lucky for having such amount of omegas "admiring" you and wanting you to own them, right?
I mean, from my point of view this fictional situation isn't entirely different than the real life phenomenon of teens who get secondary sex characteristics earlier than their peers or the conflation of "physical maturation" = "mental/emotional maturation" that negatively impacts many teens of color who lie on either side of the infantilization - adultification spectrum.
Just because you "look" like an adult, or you look older than you are doesn't mean that's how old your brain is.From an omegaverse perspective, many writers like to play into this for further "taboo-ification" of the alpha/omega trope. But, if this was a real life society, I'm pretty sure that wouldn't all be a-okay.
Using your example about the young omega - their dynamic is not their fault and it isn't really their responsibility to police how other people interact with them because of the way their body looks. Now, they or their parents may opt for personal interventions to minimize the attention they're drawing towards themselves - such as dressing modestly, using scent blockers, etc.. Regardless, the situation you are describing is one where physical and sexual abuse are commonplace and acceptable, and unlike many popular stories/aus that utilize this sort of senario - I think overtime alphas would fall out of fashion in terms of being ideal partners as they would be seen as uncontrollable, overly-emotionally, and dangerous, while betas would rise up the dynamic hierarchy to replace them.
In the reverse situation that you presented, I feel like it's almost a little more complicated because in a society that reveres alphas and alpha-like characteristics getting complimented like that would be a good thing. Of course the entire situation is extremely over-sexualized, and gives off "that one uncle everyone stays away from" vibes, but if the omegas are adults talking to a kid like that (if they stop after learning they're 15 that's sort of a different story) that's not great behaviour from them, especially considering they are then feeding the cycle of abuse that kept them down in the first place.
On top of all of this, I guess you'd have to consider what the accepted age of adulthood and age of consent are in your au. As we know, current attitudes on the subject fluctuate but most are at least a couple years older than they were - say 100-200 years ago. In the US legally it varies by state being anywhere between 16-18 years old, while globally there are some places where the age of consent is as low as 12 and as high as 21. To make matters even more complicated, several areas have addendums to the rule if partners are marriage or can be protected by Romeo and Juliet laws.
As we all know, I don't enjoy reading content that uses abuse/violence/predatory behaviors as a romantic vehicle to push the story forward, but some people are into it. For those out there who for one reason or another are writing a story or developing headcanons about this here are some worldbuilding questions I'd consider -
How young is too young? How is this enforced?
Is a bond mark legally similar to marriage in real life in the sense that bonded partners have protections that non-bonded partners don't?
If the alpha/omega had "good" parents would they still be okay with the relationship? Why or why not?
What constitutes for abuse or violence in this community?
Does the young alpha/omega know they're being abused? (as a general side note, I'm sure we all remember being 14-15 and thinking "I know exactly what's going on and I'm in control" only for a couple years to pass and to realize, "no I didn't and no I wasn't")
Peanut gallery - what do we think? How might you approach this in your own au and stories?