Admittedly, I never played Among Us, but the "sus" meme got around a lot.
If I remember correctly, there's a quest line revolving around Princess Gumdrop being an extremist. The Crystal Kingdom is getting cold as love disappears — and to hinder that Princess Gumdrop wants to ban any hate down to the smallest ounce of negativity such as harmless arguments of two beings with different opinions. So the player gets tasked to hand over letters to ponies which basically tells them that they're banned from the kingdom for increasingly ridiculous "hate-crimes".
The grey coated guard is the princess' husband Prince Overwatch who chimes in to ask you to stop all this madness and stand up against Princess Gumdrop because the highness herself is the main culprit of hate with her acts. At this point you may choose sides. ||The game assumes siding with the Prince being the correct choice which results in quest rewards.||