"A favor?" Repeated the idol as he continued to walk alongside the spectacled man. Though curious, he retained his emotionless expression, remaining quiet so that the professor would be able to explain himself. 'So it's about Haechan...' He noted to himself. He wasn't that acquainted with the ex-idol, but he did know a lot about him. He was built based on him, after all. However, Mark had always felt somewhat inferior to the ex-idol. What differentiated the two was the fact that Mark was a robot, and Haechan was human. Having no heart... Only being a scrap of metal who supposedly would only temporarily take the human's place in this world.

He was just a replacement, wasn't he?

A section of his chest constricted, but as always, the youth known as the Cheerful Idol was able to easily hide his 'feelings'. "I understand." The younger answered with a meaningful nod, having memorized and jotted down all of the professor's warnings and orders in his MRKL database. He then shifted his gaze towards the door that lead to Sooman's office, opening his mouth once more to speak.  "He's in there, isn't he? Haechan." A nod came from the professor served as his confirmation. Haechan was carefully listening to all the conversation. It was easy to eavesdrop on them since they were standing close by the door. Or probably, his uncle did it in purpose so he could hear everything. Grabbing the handle, Sooman swiftly opened the door, immediately spotting the brunette. Since the door was open so suddenly, it got the brunette startled a bit. As a result, he quickly stood up to greet him in a formal manner.

"A-ah. Goodnight, Mark-sshi. I'm Haechan, nice to meet you. And.. Sorry for making trouble for you.. to come here..."

Haechan seemed nervous, Mark noted. His heart rate sped up and he was visibly sweating. Mark didn't understand why the other was so anxious.

"Evening." He replied easily, seemingly unfazed by the awkward atmosphere Haechan had created. "It's no problem."

Sooman only stifled a chuckle as he covered his mouth.

"What's with that awkward act, Haechan..?"

Mark only observed as Sooman began to tease his nephew. Banter; this was part of human interaction, wasn't it? As he watched the two in silence, he recorded every detail within their exchange in his database. It may just prove to be useful for references in the future.