The Home of the Two

Long, long ago, in a faraway land... There was a tiny village that lived together happily with the other villages. This tiny vilage is called 'together (in latin or greek)'. 'Together' lived harmonically with the other villages. Even other villages often came to them to ask for advices. Why is it? Because the villager of 'Together' is very special.
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General idea:
'Together' consists only people that are born with his/her shared soul i.e their twins. It doesn't matter whether it is twins, triplet, or quadruplet. People in 'Together' believe that the god never let them alone in this world, thus when they are born, there will always be at least two of himself that will never be apart.  Every villager lives together with their twins until they reach adulthood - 20 years old. When they are 20, one of them will go to the outside world, while one of them will remain in the village for the rest of his/her life. The twin that lives in the village serve as connection to the twin that live in the outside world. With this, they preserve their tradition and get new knowledge from the other world without going out themselves. The Elder will decide who goes out and who stays.

The main character - let's call them Alpha until I give him proper name -  born with his twins - let's call her Beta until I give her proper name as well. Alpha and Beta are born without the elder can read any of the sign - leaving the Elder in confusion thus they live under the elder surveillance. When Alpha and Beta reach 16 years old, Alpha starts having weird dream. A voice and a soul. Alpha tells this to the Elder, and the Elder decides to send Alpha to the outside world before the rest of the village knows the secret behind them. However, Alpha tells this secret to Beta and gives her an empty crystal bottle and saying "the bottle will let you know what happens to me. no one must see this" Beta starts having the same dream but from different perspective 1 month after Alpha leaves.

Basically the dream is the truth about the twins. Their ancestors pray to god to never let him and his descendants alone again. The god agreed. Thus the god split one soul into two, and giving each soul a body. One day, the two soul must come back to one before both of them lose their 'flame' (something like fuel to live). The elders can see the 'symbol' of the one that soon will lose their flame - they send it to the outside world.

Before he is sent to outside world, Alpha realise that some twin does not exist anymore. This is why he gives the bottle to Beta. The bottle serves as connection in case something happens to either of them. While loitering around in the outside world, he meets a couple of twin who are separated from their twins. They are the one who still have their 'flame'. Alpha realised his hypothesis - some twin do not exist anymore (by questioning and stuffs) - was true. He starts to wonder what should he do to prevent either of them to cease. Meanwhile, Beta starts to realise that she can't feel Alpha's presence anymore. Whenever she feels it, a tiny star appears in the bottle. At first, she thought there is something wrong with Alpha. However, it's the other way around.