Okay so this is only what I know/remember from reading a bunch of OMEGAVERSE mangas so don't comes at me guys, I may be wrong...
1) to be mates means that an alpha has bit an omega on the back of the neck when in heat, thereby making them a mated pair. The omega can thereon only mate with the alpha during their heat. If someone other then the alpha tries the omega's body will violently reject the alpha. The omega will/could start convulsing throw up ECT. I'm also pretty sure that during an omega's heat is the only time they can pregnant. So the mated omega can only have a child with their mated alpha (if their not mated they can still have kids with another alpha if the omega is in heat)
Okay so imma explain this in detail soo sorry its long af..
*Seiji = alpha, Aiji = omega, Towa = twins omega lover*
2) I think in the beginning they may not have loved each other in a romantic way as much as they were each others lifelines to be able to exist. Later on tho they definitely loved each other in a romantic way but they are still each others pillers..they also fell for towa too!
3)So before everyone found out their gender Aiji was loved by everyone, which made Seiji feel like an outcast compared to his brother. But when they found out their genders, their roles almost reversed as alphas are revered and omega's are seen as 'disgusting hoes' (FUQ DEM PEEPS WHO SAY THAT BTW THEY ARE ADORBS). Seiji then felt superior compared to his brother (and free from being ostracized) but noticed that some kids were bullying Aiji and that they took his supressor.
Therefore when Aiji fell into a heat Seiji went into A uncontrollable rut and bit him making them a mated pair of brothers. Their family then saw their 'unnatural' closness/relationship and tried to separate them. Seiji, then regretting feeling superior to his brother who was always there for him made Aiji bite him on the neck so they were the 'same' and decided to elope. That's were it all started.
All in all Seiji started copying Aiji so no one can specifically bully Aiji for being an omega and so their parents would let them be because they are 'embarrassments' to their family. (I did skip some little parts but that's basically what u need to know)
Oh ok thank you very much! I didnt know the bite effect only works when in heat. Also wasnt sure about the love but i'm glad you agree on that and thanks for making it clearer for the copying attitude. (>×-×)>
Gotchu, happy to help ヽ(｀・ω・´)ゝ
1. What does it do to be mates?
2. Did the twins loved each other in a romantic way or they just wanted to be with eachother?
3. Why was it important to copy eachother?