General primer on the A/B/O universe the fic is set in

I wanted to write an ABO fic where the sex part wasn't as central as it is some fics I read. A lot of them tend to be about sex and I wanted it to be about the more twisty, bonding parts of it. But I know it gets confusing because the ABO thing isn't talked about as frequently or explained as obviously in the fic so I figure a basic primer won't go amiss. It won't be every little detail because some bits play into the plot and I'd like to keep them under wraps.

Basically,

Alphas=Better physical senses, the aggression and dominance parts are more social constructs and as a consequence of their senses than a concrete rule.

Omegas=Empathy, the homeliness and nesting type of stuff is again more out of stereotypes than reality.

Both are supposed to be sensitive to smells but for Alphas it's a general awareness of all smells, while for Omegas the people smells are the things they're sensitive to. Physiologically it's because they associate certain smells with emotions due to their empathy.

Children are considered Betas until they 'present' in a second puberty by the age of 21. For Alphas this puberty is in the form of irrational and aggressive behaviour mostly because they're adjusting to the overload of sensory information. Their puberty is more sudden onset with a few symptoms here and there. There's a sensory flood that happens but it happens in waves often pertaining to one sense or the other and they need considerable help to manage to control all their senses at once, mostly learning how to suppress all of them.

In Omegas the puberty is more subtle and happens in hierarchical stages so it's not as difficult for them, ultimately culminating in a 'Heat'. The 'Heat' isn't particularly sexual, mostly just intense uncontrollable empathy along with hot flashes. Omegas are isolated during this time because it can cause a lot of pain and potential dissociation to be so aware of others emotions. During their first Heat they usually have one person with them whom they know well so that they can anchor themselves with that person and learn to focus the empathy on localised empathy needs training to be weaponized, most Omegas just learn to tune into a few important people's basic emotions because it can get overwhelming.

Essentially, they're both mostly the same because they end up having to learn to suppress the heck out of their abilities in order to live with them day in, day out. There are people who learn to use their abilities to the point of greatness but those are outliers rather than the norm. The terms Alpha and Omega are thrown around more because entitles them to privileges and because they're identifiers.

The Wizarding society is chilled out about what Omegas can and cannot do. No restrictions that they need to have an Alpha guardian or anything like that but also no specific protections. The Muggle world is not that chilled out, there are a lot of stereotypes and restrictions on them along with a lot of protections, mostly based off the stereotypes. For example, even if proven, Harry burning the house down wouldn't be accepted as premeditated murder, as an Omega he would be considered incapable of it, however it would be recognised as a emotional breakdown and he would need to go through a rehabilitation process.

Most Alpha-Omega relationships result in a bond that is mostly an interplay of their abilities, the Alpha of the pair sensing the physiological comfort while the Omega is tuned in to the psychological comfort. This builds into a stronger bond as the two grow to know each other better and better.

True Alpha-True Omega pairs are rare and not documented much. There are stages in which the bond grows, the two recognise one another as their partner, the recognition being stronger on the Omega's part, a contribution of the Empathy. Next, the offering of a gift by the Alpha, a contribution of the Enhanced Senses and finally the absolute acceptance of the bond by both. Both these types of bonds can kill an Omega because during their Heat they require to be in the presence of their anchor, their respective Alpha partner. A rejection from their bonded Alpha means that the Heat proceeding the same will overwhelm them and cause them to flip out, usually ending with them taking their own life.

The presence of Magic throws the above sequence of events out of the joint and in the Wizarding world, True pairs are often seen to happen spontaneously.

Harry and Tom are both outliers to pretty much all the rules, because of course they are.

(I mention no genital differences because I still need to figure it out. One of the issues in knowing the reproductive systems in a fair bit of detail is wondering how one teeny tiny change affects the rest of the system and let's be honest, ABO anatomy usually involves more than just a 'teeny tiny' change)