Spoiler text. His little brother. Ano partner is the other blonde guy

till the day teddy manifest into an esper A class and the world (argentina mainly) was having a huge outbreak of portal gates. At the time many from banos evacuated and teddy also got into NSA guild. They move to korea while hyoseop stays in banos (btw during the 6 month hyoseop became tanned because being a farmer).
while teddy was in NSA he accidentally told about hyoseop (codename JIN) and shin haechang immediately recognize it was hyoseop and still alive in banos.
at this time massive gate outbreak, lots of s class esper was dispatched to deal with the gate including andante. After shin haechang confirmed hyoseop was alive, he plotted a ploy to pull hyoseop to join NSA. Coincidentally after andante return from the gate he gone into berserk and was send to korea hospital bound in chain. Hyoseop after seeing the news immediately goes to the telportation station between banos and korea and over there shin haechang was waiting, shin haechang then use the opportunity to offer help to hyoseop so he can go to andante to guide him without anyone knowing its him but in return hyoseop would have to join NSA contract 1 year. He agreed then hyoseop guided andante till he recovered but does not know it was hyoseop... you guys please read the novel, i read on azilatl(.)space  delete the ()