Sans and Frisk (Your Parents)

Everything happened far in the past... When Frisk fell into the dungeon, she began to resolve conflicts through action and peaceful actions, she was able to bring peace and happiness without violence. Also, during her journey through the dungeon, Frisk met a skeleton monster named Sans. Sans always loved to joke about bones and be lazy. Gradually, Frisk and Sans became friends, and after that, Frisk moved on. Also, in the end, Frisk was able to destroy the barrier that sealed the monsters, after which Frisk became a hero for the monsters...

After this, Monsters and Humans began to live in a world without war and battles, after this, Frisk also began to live together with Sans, gradually Frisk and Sans became friends, then a couple... And then Frisk and Sans got married, and after this, Frisk and Sans had a child who was human but had a "Merged Soul"