Fanmade theories

It's getting really confusing

Like why does woo hak have those flashback of past when ki ho is someone else

And ki ho is someone else because the person who is ki ho he remembers himself for his past friends to have contacted

It's most probably that bo gyeol is ki ho

But the other thing make me come up with a different story

The theory

Woo hak is ki ho. But he hurt his head and forgot every thing but eventually he had everything written in a diary all the moments as he always used to remember mom ha but never talk to people's and

No gyeol after the accident got his hands on the diary and read all of it which is why he used to wait for Mok ha at that place not ki ho as his glasses were gone (bo gyeol is never shown to use contact or having poor eyesight yk cause if he had wook hak could have already copied him)

Which is why when bo gyeol met mok ha he bought her shoes and at the end the song he could feel his brothers emotions as she was singing as he read ki ho's diary

While without any connection woo hak felt a good bond between him and mok ha.

And about his school friends talking to ki hko. Bo gyeol as an adult must have reached out to ki his friend ofc to get info on Mok ha for his brother introducing himself as ki ho cause he read how ki ho's father used to abuse him and incase he found out it would be bo gyeol so to take it upon himself.

And at the end it's just the hypothesis

Well but if really bo gyeol is ki ho then he and woo hak has to be either twins or nothing at all

Not the half brothers

Just step brothers

I think that Bo Geol is Ki Ho. 

What I think is that after Ki Ho was in the hospital he was seperated from his dad and found a couple that took him in (Woo Hak's parents).  At first they probably introduced Ki Ho to Woo Hak but Ki Ho's dad found out where he lived. I think that Woo Hak has memories of Ki Ho's dad because the dad found out where thye lived and tried to take Ki Ho back, and thats possibly how Woo Hak got his brian injury. Maybe Woo Hak was in the way trying to protect Ki Ho. Because he lost all of his memories, it was probably easier and safer for Woo Hak's parents to just pretend that Ki Ho is Woo Hak's brother and gave him the name Kang Bo Geol. This way Woo Hak's ignorance would help them not get caught again and Ki Ho could be safe. I think that Bo Geol is lying about being Ki Ho because 1) he's probably guilty that Mok Ha was on the island for 15 years and 2) it gives the potential for Ki Ho's dad to find him again.

 I especially believe in the second reason because once Woo Hak told Bo Geol that Ki Ho is waiting for Mok Ha, he immediately started running to save her. This is because he knew it was a lie. Ki Ho couldn't be meeting her if he is Ki Ho. 

It's only chae jong heop the ML because it's his back silouhette when the boy grows up

I don't feel like the writers are gonna throw in a diary loop it'd be far fetched. 

If I'm boiling it down to Kdrama I've been watching for the past 7 years. There's been very few where the lead is unexpected. 

We all know first of all Bo Geol is lead. And as of ep 4. His appearances are increasing slowly with Mok Ha . U cannot make a male lead Cannon fodder and this silent if his character doesn't have a story to tell. It makes no sense if he's not Ki Ho and has presense of emotions only shown through his eyes if he doesn't have a major pov coming on. There are lots of cut scenes that include him...

I'd be very disappointed if Bo Geol is in fact the male lead and not Ki Ho. No unnatural but very unexpected in a negative way. When u make a character u have to have story build for u to be attached to that character. As of now we are very much known to Woo Hak story and getting attached to him. You're telling me Bo Geol is male lead? Give me a story give me a past I can attach his character to ,then and only then I accept him a love interest in whole form. But if u make a character and just say he's protecting his brother,oh and his brother is the one who protected this girl and helped her BUT she chose to be with Bo Geol? That's very unsatisfactory as a viewer tbh real life is far from it so considering from a viewer's perspective.. that'd be a bad choice from female lead and writer all together. At the end of the day I'm here to watch a series that makes me want to feel for the characters and root for them in fullest. And many would like the male lead with trauma over the unexpected male lead. 

So I'd take a blind bet that, Bo Geol is Ki Ho or I'd be like

..damn she pulled the same shit as Start Up? I'm Outta here 

Well some things are clear now

Bo gyeol and woo hak are real brothers

And woo hak is the older brother or maybe they are twins still woo hak isn't ki ho but he was abused too as we can see the flashback,his mother said those same words too making him similar to ki ho but still he ain't it

That abusive fvcking father is psycho now he attempted to kill that childhood friend of ki ho

And woo hak is so sure about him being ki ho cause he went through all that ki ho did and he can relate to all of it

And about Mok Ha's love interest I am not sure it could be anyone of them even ki ho or the other brother

It doesn't have to be ki ho

But both of them are gonna like her so there's a pretty bad second lead syndrome awaiting for us ?