You and XChara were in the royal guard. You were both training right now. The exercise was to hide in case of an emergency or something backfired. Simple, stay hidden until a signal was given and don't get compromised. Easy. So people got into groups, (you with XChara) and were given 15 minutes to hide from Undyne and General Mettaton. You and XChara ran into a small storage that had a crawl space in the storage space. It was a tight fit for both of you. The small space was also toasty from your combined body heat which leads to now. You two are practically on top of each other trying to cool down from the heavy armor you were wearing.