They didn't start off as friends... it was nowhere near that. Kyungsoo was part of the 'nerdy' block... Jongin was part of the 'bully' block... So by default they are sworn enemies. ----Well, at least that's Kyungsoo thought--- The bet was a JERK move on Kyungsoo's part... He just wanted to prove something to those bullies But as the movie CRUEL INTENTIONS said: "In the game of seduction, there is only one rule; NEVER FALL IN LOVE..." ...but he did... he FELL in LOVE with Kim Jongin... ...and when he started to acknowledge his feelings for the younger one... It was already TOO LATE... ....Jongin already HATES him... ....Kyungsoo WANTS him BACK but Jongin doesn't BELIEVE in him anymore... ...Kyungsoo worked hard to gain his trust again... ... And when he finally did... ...when they are finally HAPPY TOGETHER.... ...FATE decided to be CRUEL... ...and so once again, Kyungsoo decided to be a JERK again... ...but this time though... ...it was because... he LOVES JONGIN very much...