I really like the Monsters x reader story. Imagine if Reader got preggers and didn't know who the dad is. That would be one very intense fight amongst everyone.
I suppose it would be rather easy to figure out the paternity once the child is born. If it’s half lizard, for example, it might be safe to assume the many-eyed screeching creature wasn’t involved in its creation.
During pregnancy it could be once again the time for the mayor or Monstertown to interfere and keep Reader away (they have no idea how fragile humans are so they’d rather not risk stressing it out). To maintain the peace he might even turn it into some sort Olympic event, where only a handful of monsters that make it to the finals have a chance to impregnate the Reader as well. I won’t go into detail because I have another ask about a motherly Reader that triggers the monsters’ breeding instincts 👀