Well, perhaps there could be a fanfiction where a new deity emerges with the power to manipulate the very essence of the gods. This deity targets Artemis and causes her to become pregnant. Apollo, being very protective of his sister, decides to fight against this new threat. The story could explore the relationship between Apollo and Artemis in a new light, as they struggle with this unexpected situation. It could also show how the other gods react to this strange occurrence, some might be sympathetic while others could see it as a sign of weakness or a threat to the order of the pantheon.
One idea could be that Apollo and Artemis have to team up to save their home in Olympus from a mysterious dark force. They put aside their usual sibling bickering and use their combined powers of the sun and the moon to fight it.
One plot idea could be the challenges they face in a world that is not fully accepting of their situation. They might have to deal with the judgment of other characters while also preparing for the arrival of the baby. Another could be the discovery of new powers or abilities that are awakened due to the pregnancy.
Well, perhaps Apollo and Percy are in a secret relationship. The pregnancy could be a result of a magical experiment gone wrong. They then have to hide it from the other demigods and gods. Percy might be worried about how his friends will react, while Apollo is more concerned with the divine implications. They could go on a journey to find a way to reverse it, but along the way, they start to bond more with the unborn child.
It could be that Artemis is influenced by a new power she has acquired. She might be exploring a new aspect of her divinity, like a darker side of the moon's power. This new power is too much for her to handle at first and when Apollo comes to check on her, she accidentally unleashes it on him. This would then lead to a story of Artemis trying to master this power so that she can never hurt Apollo again, and Apollo having to deal with the physical and emotional pain of being hurt by his sister whom he trusts so much.
Perhaps in this fanfiction, the pregnancy is a result of some sort of curse. The two have to go on a quest to find the source of the curse and break it. Along the way, they face many challenges, like battling ancient monsters that are awakened by the abnormal situation. They also have to deal with their own changing feelings towards each other as they are forced into this unexpected and rather strange situation.
One idea could be that Apollo and Hermes team up for a musical competition across the realms. Apollo uses his musical talents and Hermes uses his speed to spread the word and gather audiences. Another could be a story where they swap their powers for a day and have to deal with the consequences. For example, Hermes struggles to control Apollo's sun - chariot while Apollo has a hard time with Hermes' winged sandals.
A plot could be where Batman discovers that Artemis has a unique connection to an otherworldly power source that some bad guys are after. They go on a quest to protect this power source. For example, it could be a magical amulet that Artemis has unknowingly been in possession of. Also, they could have a story where they train together. Batman teaches Artemis some of his detective techniques and in return, Artemis shows Batman some new combat moves. This could strengthen their bond and lead to them being a more effective team against threats.
One idea could be that they go on a secret mission together outside of the team. Maybe they are sent to infiltrate an enemy base where they have to rely on each other's skills more than ever. Wally's super - speed could be used for quick escapes and distractions, while Artemis' archery skills are crucial for taking out guards from a distance.
An interesting plot could be that a prophecy states that only a union between Apollo and Artemis can save the world of the gods from a great darkness. At first, they are horrified and resist the idea. But as the signs of the approaching doom become more evident, they start to consider it. Along the way, they face opposition from other gods, especially Zeus who is enraged at the thought of such a relationship. This forces them to go on a journey to find a way to fulfill the prophecy without actually going against the moral code of the gods. It could involve them seeking the help of wise old gods or magical artifacts.
One idea could be Percy joining the Hunters of Artemis on a special quest. Maybe they are seeking a powerful magical artifact that has been lost for centuries. Percy's unique skills as a demigod could be really useful in this situation.