As I have promised or mentioned before, I will explain a bit about mates in master's series. But first, I will again tell you about the war between the Klan and our heroes. 

You can call them aliens even though I, as the writer and the creator of this series *can I say that? hahaha*, would likely to think them as just normal humans but coming from another realm. It's like....Narnia? Like the Pevensies but it's like the Pevensies are coming from Narnia to the Earth, not the other way around. But our heroes and the Klan have this immortality once they arrive on Earth. If they go back to their realm, they will age normally just like humans on Earth. It is most likely that if humans go to their realm, they will be immortals. 

Why do they need humans as their mates? Simple. They have no same people around them. The war have ruined the lineage of the realm. If they want to be still existed, they have to be with locals, which is in this series, humans. 

Our heroes and the Klan were part of royal-blood families that were appointed to guard the Throne of that realm (MAYBE I WILL NAME THE REALM 'EXO'). There are twenty four families, each has superhuman power which can help them to do the ultimate job. There are twelve super powers, so you can imagine that there are two families who have same power. Their power came from...well, you can watch MAMA music video if you want to know. Yeah, the Tree of Life. In this series, there is group of women who swears to protect the Tree and embrace its power. They are the one who are called as 'oracle.' In order to protect the power within the families, oracles do the thing that we know: choosing the mate; choosing the women who will marry the leader of those families. Those who are chosen are actually chosen by the Tree itself, but the oracles are those who read and tell the choice instead. The Tree also can control those who have its power, especially about their emotions toward their opposite . That is why when our masters see their mates, they will be, like, addicted to them. This is controlled by the Tree. Also what happened to Sese (read Fourth Story: Master of Wind) is the work of the Tree. He indeed was attracted ot Eun Soo but once he saw Soo Eun, his feelings to Eun Soo was gone just like in a blink of an eye. 

Back to the families, their union broke apart when the last King of EXO appointed his younger daughter instead, Princess White, to be his successor. Many of the citizens believe that one of the Klan's families is aiming to become the king and that is why the Klan attacked the ceremony. However, that is not true. The truth is the oldest daughter, Princess Black, wasn't satisfied with her father's decision. She wants the throne for herself, thus she felt betrayed when her father chose White instead. And so she gathered those protectors, and twelve of them, each represents twelve powers, agreed to serve her and followed her, while the other twelve whom each of them represents the twelve powers, were against the idea and tried to plea the King to punish them. But the King couldn't punish his daughter and believed that Black would not be that evil and sorrowful; he believed that Black might still have love or White. 

But his decision was wrong and he with his wife were killed in the hands of Black.Tree of Life was burned down because of that attack but it was after the oracles saved its soul and trapped it in their bodies as what our heroes' ancestors asked them to. White was rescued even before the enthronement happened by Lay's ancestor (Master of Healing at that time) and hid her with the help of other masters who kept their loyalties to the late king. They also believed his lineage to keep White without their knowledge so her safety would be more secured; less people know, the secret will not likely out easily. That is why Lay is the only one who knows where White is in this series. 

These people kept fighting until they realized that their land was ruined because of it. The citizens also were divided to two parts. Our heroes' ancestors realized it first and they still wanted to save their realm, thus they jumped into Earth with their followers. The Klan's ancestors saw it and with Black and their followers, they jumped into the Earth, following their opponents. That is when they knew they were aging so slow, even could be categorized as immortals. They also realized that their people were so less-populated than it should be. The Klan realized this and they did kidnap two oracles to be their guides against our heroes. So both side have their own Tree of Life's parts; none of them have one full soul of it to guide them anymore. All the oracles then worked to read the parts of the soul that they had to read the future, including the mates. That is when the Tree chose humans instead. That is when the practice of 'sharing blood' between the immortals and humans was founded, and the guide book (read First Story: Master of Teleportation) was made. 

As for now, there are twelve leaders in our heroes' group. They are: 

1. Xiumin, Master of Ice. He can control ice and frosting things; you can say he is Elsa 'Frozen' in man's form related to his power. He is, however, slightly powerless when there is no water or air since ice can only be made with those two, thus when he faces the battles, he has to be close to Suho or Sese or both of them. He has already had a mate. Her immortal name is Tael and her power is to control the snowflakes (you might can see the demonstration of her power....if I want to insert it into the stories LOL haha). Tael's real name is Hwang Sook Ja and she was coming from Silia Kingdom. This couple is the only couple who has children, not child: one eight-year-old looking boy and toodler daughter. 
2. Lu, Master of Telekinesis. He can lift things up with his mind, and not just things, he can control human's mind too with now he has known how to do it thanks to Lay. He is one of the most powerful one and doesn't need specific other masters to beside him when he does his power. He has already had a mate. Her immortal name is Juon and her real name is Soo Hwa. She was a gisaeng from Joseon Era and they met when she entertained him and some of his fellow 'Chinese Ambassadors'. Lu immediately asked to spend the night with her after he saw her dancing and she kept being asked by him to accompany him in his days of being the ambassadors.At the last night, when he wasn't supposed to visit her, he ran into her and told her to follow him if she wanted the freedom. She followed him and escaped the gisaeng house while learning about his true identity then agreed to become his mate. You might know her as Se Mi in this series as it is her name in this timeline. Together, they have just got a son. Juon's power is to do telekinesis but in smaller scale.
3. Kris, Master of Flight. He can fly by himself and a fan of everything related to sky or flying things, including dragons. He has a dragon and he has once given its dragon's child to Chan who then is trained to become the immortals' superpower dog (read Second Story: Master of Fire). He just got married to an American woman named Emma and Emma becomes her immortal name, even though Uru and other mates call her as Em. He, just like Lu, doesn't need other masters to do his power well. He hasn't gotten the heir. Em's power is just same as Kris but in smaller scale. 
4. Suho, Master of Water. He holds one of four elements' control power. He can do anything with water and also can breath in the water. He needs some masters beside him to maximize his power, especially Xiumin. They can collaborate to make things bigger than usual with their powers. His mate is Uru and her real name is Choi Yeo Rang, coming from Baekje Kingdom. She was ordinary girl living with his family when Suho and some of his brothers came to her village. On one night, Suho kidnapped her and some other girls because of oracle's tale that his mate was coming from that village. When he found out she was his mate, he kept her with him and made her scared because of it. But now, it is like a  turned table for them: Suho is rather scared with his wife. He doesn't have the heir. Uru's power is smaller scale of Suho's. 
5. Lay, Master of Healing. He is like the most religious of them and believes so much to Tree of Life. He is the protector of  oracles and also the only one who knows where White is. He never confronts anything in any kind of battle as his power is not for confronting; it is defending him. He usually stands behind the troops and his brothers, guarding the oracles. His mate is Cello and her real name is Kozuo Taka, a Japanese woman. She was coming from Meiji Era and met Lay when he became a merchant from Qing Dynasty as her father was also a merchant. Her power is actually smaller scale from Lay but it is more specialized in reading aura. Together, they have trained lots of mates in their pack since both of them are guides of spiritual section in their lives. 
6. Baek, Master of Light. He has this power to produce light within his body, although it will not burn anyone (because burning is Chan's specialty). He is just like Lu and Kris; he doesn't need some other masters to strenghten his power. He is usually at the front line with Kai in the battle since with his power, he can be the human's shield. His mate's immortal name is Afra and her real name is Oksana Burkhanova. She is, at this time, the youngest mate (she was made as an immortal at the age of 19). Her power is to re-directing light and reflection-related power (you may know how if I want to reveal it hehe). They have an heir named Abe and he is at the same age with Yo. 
7. Chen, Master of Lightning. He has the power to control thunder and lightning, even to re-direct them. He is bounded to be with Sese if he wants to maximize his power. Thunder and lightning can be controlled from his emotion, too. When he feels insecure or gets angry, those things can represent his feelings. His mate is Song Dong Ah (read Third Story: Master of Lightning) and they just got married. Dong Ah's immortal's name hasn't been created yet but she favored to be called Zandra, since she says it sounds like a clothing line. Dong Ah's power is limited only to produce lightning but not with thunder or redirect lightning. 
8. Chan or Channie, Master of Fire. He has unlimited power of fire, that is including controlling its flow and producing it from his body. He can make either red or blue fire, or any other fire with different colors. He is much affiliated with Kris, because Kris is fond of dragons and dragons also produces fire like him. His mate is known to be Gigi and her mortal name is Kang Hye Ji. Gigi is the daughter of late Lord of Strength, Neri (who is also sister of the current Lord of Strength in the Klan's pack) and an ordinary man coming from Joseon Era, which makes her half-immortal - half-human. She has traits of immortals, such as long-lasting youth and superhuman power, but she also have some traits of humans, such as sickness or dying of natural causes faster than pure immortals. Since Gigi also has Strength (mostly on soil / ground), it affects her fire power. She can't produce fire like Chan, but she can burn people inside their flesh when she touches them. 
9. Kyung, Master of Strength. Don't judge a book by its cover is a perfect example of him. He might be the smallest one but he is the strongest. His power is at the best when he is connected to the ground. His mate is Sae and her real name is Delphine Condos (can you guess from where she is?). They met when Kyung was taking a round trip with Kai throughout Europe in 1930s. Her power is a reflective of Kyung: she can produce her power when she isn't on the ground better than on the ground. Therefore, she is much closer to Sese and Kris because their powers seem to be alike. They have a son named Yo. 
10. Tao, Master of Time or Time-Traveller. He can rewind and stop or play with the time, but his brothers rarely use his power because of the consequences of playing with the time. He doesn't need to affiliate with others and can play his power alone (also playing and pranking his brothers with his power). His mate is Lin Hui Fang, thus her immortal name came from her surname, Lin. They met in the time of Chinese Civil War. Lin's power is smaller scale of Tao's. Lin was about to be killed when she still adjusted an immortal life in their last battle (until this time) with the Klan. At that time, Lin and Sae were the youngest and the newest mates. Lin, at this time, is pregnant with the heir of Tao. 
11. Kai, Master of Teleportation. He is the swiftest and the fastest one among the brothers. He might not control anything but his ability can either make the opponents confused or easily attacked by him. He can jump from one place to one place, ignores the seas and oceans, and with collaboration with Tao, he can also jump throughout the time. His mate is Jung Han Byul and her immortal name is Byul, taking from her nickname when she was growing up under the wing of Kai. Byul's power is smaller scale of Kai but she can't do time-jumping like Kai. Byul was once a daughter for Kai before he knew that she was his mate all along (read First Story: Master of Teleportation). 
12. Sese, Master of Wind. He isn't just controlling wind; he also can control every element of air, that is inclding clouds or other gas in this world. He can even choke people with using the air surrounding the opponents, a bit similiar to Lu's power, even though Lu choke them with blocking the nerve inside their brains. His mate is Jung Soo Eun and if she becomes his mate, she will be the youngest one to be made. Her power is she will have no super power in wind, but she can block the wind (wind shield). So it's a reversal of Sese's power. 

That's it! Thank you for reading this!

PS. Can someone draw those mates? I can't draw but I want to share my imagination of how they look like to all of you the readers :)