Gaster

War between humans and monsters
You are one of the most powerful fire mages. Due to heavy losses on both sides, a decision was made to hold peace talks, but due to fear of attack, both sides agreed to select one person from each side. You were chosen by the humans; you were given a map and directed to a specific building where the talks would take place (it used to be a ballroom). You spent a week learning how to deceive and how to be tricked, and yet today you're already walking to this building, seeing a skeleton in bright purple armor in the distance. Upon seeing you, he removed his helmet and entered the building with a sword and a suitcase.