Kyungsoo is a shifter. He can't change into many things. He can change into only one; a human. He is a wolf. Not those hideous wolves you see in Twillight. He looks just like a normal wolf, except that he has maroon fur. He used to be in the Red Sun pack until he got kicked out because he was seen with a human. A real human. Ever since he got kicked out, he had been wandering, from the North to the South. 

Kai is a human. In fact, he was the human that was seen with Kyungsoo. He almost got his arm bitten off. Luckily, Kyungsoo was there. He and Kyungsoo were best friends until Kyungsoo got kicked out. Kyungsoo refused to talk to Kai after that. Little did Kai know, Kyungsoo was a wolf.

Kris is one of the alphas in the Two Moons pack. He adopted Kyungsoo when he saw Kyungsoo wandering around in the Two Moons' territory. 

Suho is the beta and half-brother of Kris. He didn't agree to Kris' decision of adopting Kyungsoo to the pack. But little by little, he accepted Kyungsoo.

Other members of the Two Moons pack are also shifters.