But let's look a little bit further

When Minwoo had entered Dongwoo's office earlier, while Dongwoo was sleeping, with his head on the desk, he heard a sniffle.

'Is he crying?' he thought and went to check, only to find Dongwoo's face flooded with tears.

The sight was a real heartbreaker and Minwoo felt he might be the reason behind it because he kept hearing him mutter,

"No family. No family. No one."

If his presence was the reason his brother was in pain, was there any reason for him to stick around?

But he didn't want to leave. He couldn't leave.

This was his opportunity to make right the wrong of the past. The past...

The past that he could never forget. The past he wished he could erase or rather, change.

If he could go back to that time, he would've never acted so immature, even if he was young. He would've been more like his brother. Mature.