The first of the Twelve to be placed in the care of his Guardian is Kai. Kai is very young when the Red Force attacks, the second youngest of the Twelve. His powers are far from under control, and the responsibility of his tutoring falls on the shoulders of his Guardian, Taemin.

Taemin is a nanny in London, and no one sees anything out of place when he takes another child into his care. Kai grows up playing with the other children in Taemin's care, children of rich families in the area.

Occasionally, he and Taemin travel to Scotland to meet with Sehun and his Guardian. Kai cannot remeber Sehun from before coming to Earth, but their friendship is much the same as it had been before. 

As Kai grows older his powers become more potent and more difficult to control. He often finds himself teleporting into the kitchen straight from his bed, or into his bed after a long day at school. Sometimes he phases straight onto the street, trying to get to school. One day after a bad day at school and a scolding from Taemin, he'd teleported all the way to Sehun's house in Endingburgh. Needless to say this had caused a large fright for Sehun and his Guardian in their home, and a frantic Taemin calling twenty minutes later.

As Kai and his powers grew, so did his curiosity. For years, Taemin had explained his realtion to Kai as a kind of adoptive father, never saying anything about Kai's real parents, saying he would explain when he was older. Saying that it was complicated. Eventually fed up with his Guardian's tight lips, Kai went to the government office to find information on his parents, only to find, that he had no records predating Taemin bringing him into the country from South Korea. Even more confused than before, Kai had come home angry and emotional and demanded an explaination. And so Taemin had explained in full detail, who he was, and who Kai was. He explained that Kai was from another planet, one he was destined to save. Taemin told Kai about how his parents had contacted him mrer days before their death to ensure that there child would be taken care of on Earth. Explained his trip to Korea to pull Kai from a crater along with the other Twelve.

Kai had cried for hours, unconsolable. He wasn't human, his parenst were dead, his friends were scattered across the world, and he couldn't remeber a moment of his home planet. No recollection of his parents of his friends, or other parts of his family. And he was supposed to somehow save another world, one he couldn't even remember. 

After this revelation, Kai visits much more with Sehun, and the two grow nearly inseperable. Teleportation is a helpful power when your friend lives four hours away. Then constant visits with Sehun help him learn to use his power better, sometimes taking Taemin along with him for a joy ride. Sometimes he brought Sehun back with him, and Taemin always welcomed the other alien. Eventually Taemin takes Kai out of school and allows him to train alongside Sehun as much as he wants. Both of the boys' powers improve tremendously.

Taemin also explained that when Sehun turned 18, he would be reunited with his friends, with the Twelve and they would return home, to hopefully defeat the Red Force. 

That was until, the Red Force attacked.