The change in its appearance can make it scary. For example, if its usually cute yellow fur turns dark or if its bright red cheeks become a sinister red glow. Also, if it starts to behave in an uncharacteristic way, like making menacing noises instead of its usual cute sounds.
In many pikachu scary stories, the sudden change in Pikachu's behavior is terrifying. It goes from being a lovable Pokémon to something aggressive and unpredictable. For instance, when it attacks without any provocation or starts to make inhuman noises. Another really scary aspect is when Pikachu seems to be under the control of some dark force, and it uses its electric powers in a way that is more harmful and destructive than normal.
There's a story where Pikachu entered an abandoned power plant. In there, it seemed to be haunted by the ghosts of other Electric - type Pokémon that had perished long ago. Pikachu's behavior became erratic. It would suddenly disappear and then reappear in a different place, its eyes filled with a terrifying emptiness as it stared at anyone who dared to enter the plant.
There was a Pikachu in an old, abandoned power plant. The place was filled with broken machinery and eerie silence. Pikachu started to feel a strange coldness. As it explored, it saw a figure that looked like a distorted Pikachu with red, glowing eyes. This strange Pikachu let out a horrible screech. Our Pikachu was terrified and tried to find a way out, but every path seemed to lead it closer to the menacing figure.
I'm not aware of any specifically popular 'pregnant pikachu fanfic' stories. Given the rather unusual nature of the concept, it may not be as mainstream as other fanfics. However, in the vast world of Pokémon fanfiction, there could be some out there that have a small following among a very niche group of fans.
Obviously, the main characters are usually Pikachu. But sometimes, there could be other Pokémon that play important supporting roles. For instance, a Pichu could be a sidekick or a younger Pokémon that the Pikachus are protecting.
One interesting plot could be two Pikachus from different regions meeting and learning about each other's unique electric attacks. For example, one Pikachu might know a special move that the other has never seen before. They could then teach each other and become stronger together.
Fanfiction is a very creative space. In a 'pikachu pregnant fanfiction', the author might explore how pikachu's pregnancy could impact its relationship with its trainer or other Pokemon. They could also create a whole new story arc around the upcoming baby pikachu, like how it will be raised in the Pokemon world, and what kind of abilities it might inherit. But again, this is all in the realm of very creative and often niche fan - created stories.
When Ash was in a difficult situation and was about to give up. Pikachu used all its energy to cheer Ash up, giving him a big electric shock to jolt him back to his senses. This selfless act of Pikachu is a sign of their great love for each other. Their relationship is not just about a trainer and a Pokémon, but a deep emotional connection.
One popular male Pikachu fanfiction could be about a male trainer's special bond with Pikachu as they journey through the Pokemon world, facing challenges together. It might focus on their friendship growing stronger with each battle they win.