You were on the train, trying to get back to your home. You had been staring at the window, right until you heard the intercom announce that it was coming up to your destination. You stood up, and barely missed grazing a kid. So, you apologised.

"...Did you just apologise..? I should be apologising."

They gave a curious expression, before giggling with a childish smile. Their voice was rather high pitched..What should you do?