After the events of Undertale, you were another unfortunate human who fell into the ruins, being received by Toriel for your subsequent meeting with Sans the skeleton, with the difference that this time, Papyrus would not arrive at the place, since only Sans was I was patrolling the place

Your stay was actually quite good, because even King Asgore personally invited you to explore his castle, you explored the different areas of the place, you practically explored 100% of the monsters' home

Although not everything was pink, because while you were walking, you came across a boy (or girl) who was injured, so you quickly took him in your arms and took him to your house to heal him

Since that moment he has not separated from you, because he practically considers you his savior, although from time to time he is a little strange, because he gets very possessive and from time to time crazy when someone tries to approach you to touch you or flirt