It's all started after his trip to the state to see his family. Bobby didn't think about it much but soon it started to bother him. 

flashback. 

Bobby was as usual, just joking around with with brother after dinner. It was their casual banter about everything and nothing at all but then they somehow end up with the topic of s, more accurately at how close the Trio Kim are.

"Hahahaha, it's not like you are gay right? The way you look at that Han-Bin kid is pretty convincing to me," 

His brother have meant it as a joke,  but there something amiss with his brother tone and the way that his gaze flicker at Bobby's face, it's all seems to be so serious and all trace of humor is wiped off from Bobby's face as he look earnestly at his brother's face

"I'm still the same Ji-Won--- The CYD Kim that you once knew before I went to Korea, I'm still the same Bobby from 4 years ago ok? Nothing changed." 

His brother might have laughed him off, messing his hair in the process saying something about how Bobby can't take ajoke but Bobby can actually see his brother much more relief stance after. 

end of flashback.

Bobby didn't want to think of it. He really thought he have forgotten all about it, convinced himself that there is nothing he should worry about and continue being his usual bubbly, annoying self after he returned to Korea

But, it seems like fate didn't want him to forget about it. 

Joy, the contestant from SMTM3 and also part of the Illionaire team. They spend enough time together whilst brain-storming for their upcoming stage on SMTM with Chammy, Dok2 and The Q that they are considered close. 

Her slip up reminded Bobby of the night where his brother was supposedly joking with him and suddenly Bobby is not so sure anymore 

"I thought you and B.I are a couple y'know-- with those hand holding and stuff and the way you would look at each other eyes, I seriously thought you are gay. So sorry bout that,"

He didn't know how that topic even come up with the two of them but it did and it have bother Bobby so much when it shouldn't. 

He was sure of his uality but then after two people confronted him about it (albeit in a joking manner), suddenly Ji-Won is not so sure anymore. 

He always noticed how his eyes automatically look for Han-Bin whenever he can just to make sure the younger is there and is within his eyesight. Bobby shrugged it off as an older brother looking out for the youngest but he failed to notice how he seems to in much better mood whenever Han-Bin was around.

He also noticed how they always sleep together (albeit, sometimes, no cuddling included) when it was late and Han-Bin still have not yet to finish his song but determined to do so in the small room inside the practice room. Bobby shrugged it off as looking out for a friend but he failed to notice how he seems to sleep better with the knowledge of Han-Bin is safe and not alone.

He noticed how he easily succumb to Han-Bin's words but he shrugged it off with an excuse that Han-Bin was the leader so he should do what he want to do. He failed to notice how his heart start picking up it's rate when Han-Bin flash him a smile whenever he follow along with whatever the younger want to do. 

", this gotta stop."

p/s. this is not going to end fluffy-ly.