Villains are the ones who will keep the story going by harming/chasing/other your main character(s).
In a Man vs Man story: The villain will be a physical being, a human or animal, depending on who you choose to write about. It could be a spider, if that’s what you character fears. The villain could be a creepy dude in a black trench coat and a briefcase with sunglasses. You have many possibilities here. I suggest…
– They have something/someone the main character wants or needs
– The main character has something/someone the villain wants or needs
– They are both capable of the same things (if it’s a fantasy world, they could both be excellent sword fighters…)
– Pick a personality and stick with it: The villain is either serious, or hilarious. They can’t be serious but then tell a joke. They’re threatening, or makes bargains. They’re smart, or have a henchman do it all for them. They’re strong and tall, or they have numerous bodyguards. What you character is like will determine how they act.
In a Man vs Nature story: The villain would be something found in nature, like a storm or tornado, tree or ocean. A few ideas I will suggest . . .
– Your main character has to stop a volcano from erupting (like in How to Twist a Dragon’s Tale by Cressida Cowell)
– Escape from a cavern or hidden fortress below water. Perhaps flee from a tsunami.
In a Man vs Self story: The villain is something the main character struggles with, like stress or depression. It is something within them self they are trying to overcome or fight.
– Mourning or grief
– Stress/Anxiety/Depression (S.A.D.)
– Hatred towards someone or something; an old grudge
I hope this post will help you develop your villains! Happy writing!