The plot might involve them initially being rivals. Doomguy, with his brute force and tenacity, and Quakeguy, known for his agility. They could start off competing but then realize they need to work together. For example, they might find out that a new type of demon is emerging that has characteristics of both the Doom and Quake universes' foes. So, they combine their skills, Doomguy's experience in close - quarters combat against demons and Quakeguy's ability to navigate complex and dangerous terrains quickly, to take on this new threat.
The theme of self - discovery is quite prevalent. The human characters in these fanfictions often discover new things about themselves while in the pony world. They might find new strengths or overcome personal fears. Also, the theme of magic is common. Since ponies have magic and humans usually don't, the interaction between human and pony magic can create interesting storylines.
Ash is often a popular character in such fanfictions. Since he has a long - standing relationship with many pokemon in the original series, it's easy to imagine new stories where his bond with pokemon takes on new dimensions when meeting humans in different situations.
The Doomguy was once a marine. He was sent to Mars to investigate some strange happenings on a Union Aerospace Corporation (UAC) facility. The UAC had been messing around with teleportation technology and had accidentally opened portals to Hell. Doomguy found himself in the middle of a demonic invasion. His initial experiences on Mars were filled with fighting off hordes of demons, and this was just the start of his journey to become the ultimate demon - slayer.
It can start with mutual distrust. Doomguy is used to killing demons, and the female demon is afraid of him. But when they are forced into a situation where they have to rely on each other to survive, like being trapped in a small area surrounded by more powerful demons, they start to see each other in a new light. They begin to communicate, first out of necessity, and then gradually become more open with each other.
A common plot is a human befriending a pokemon in a more in - depth way than just being a trainer. For example, they might share their daily lives, like the pokemon helping the human with household chores using its powers, and in return, the human protects the pokemon from those who might want to harm it for its powers. This shows a more equal and emotional relationship between the two species.
In a 'Lion King 2 meets Humans' fanfiction, perhaps the humans are lost in the wild. The lions, led by Kiara and Kovu, find them. At first, the humans are scared, but then they notice that the lions seem to be showing signs of protection rather than aggression. The fanfiction could explore how the two species learn from each other. For example, the humans might teach the lions about some simple tools they use, and the lions could show the humans how to survive in the wild in terms of finding water sources and safe places to rest.
The key elements include the Union Aerospace Corporation (UAC). Their unethical and dangerous experiments with teleportation on Mars were crucial. Doomguy being a marine is also important as it provided him with the discipline and some level of combat ability. The sudden demonic invasion that he had to face on Mars was the turning point. It forced him to adapt and start his journey as the Doomguy. Without these elements, his origin story would be completely different.