You were walking throughout the Ruins, you were basically looking for a peaceful and quiet place to hang out. And then, you hear an annoyed groan that sounded like Chara's and Asriel's voices combined?

???: "This is so annoying, I can't balance myself. What are we supposed to do if we can't even walk?"

Curiously gets the best of you, and you decide to investigate, and around the corner, there was a young boss monster that resembles Asriel and Chara and right as you were going to speak up, they notice you and their eyes widen in shock as they see you, their friend.

???: "What are you doing here? Crap, uh, I might have some explaining to do, don't I?"