One idea could be a story where a young duelist discovers the power of Starving Venom Fusion Dragon in an ancient ruin. They then have to learn how to control it while facing off against powerful opponents.
One common theme is the clash of different dueling styles. Since Yugioh and GX have their own unique styles, in crossovers, seeing how they interact is often explored.
Aster could get hurt in a training accident in a fanfic. He might be trying out a new and dangerous dueling technique. Since he's always pushing himself to be better, he overestimates his abilities and ends up with a minor injury like a sprained wrist. This could then lead to a sub - plot where he has to learn patience and the importance of proper training.
She could be a shy girl named Lily. She has long purple hair and big blue eyes. Her dueling style is very defensive as she uses a lot of trap cards. She's often underestimated but when she gets into a duel, she shows her true potential. Her deck is based on water - themed monsters like mermaids and sea serpents.
One great 'yugioh yugioh gx crossover fanfiction' is 'Duelists United'. It brings together characters from both series in an exciting new adventure where they have to team up to face a powerful new threat. The duels are well - written and it stays true to the spirit of the original shows.
In a Yugioh GX fanfiction where Aster gets hurt, it could be during a duel. Maybe his opponent uses a powerful card that backfires on Aster, causing him physical or mental harm. For example, a card that creates an illusion of his worst fears, making him stumble and get injured as he tries to escape the illusion.
One great Yugioh GX OC harem fanfiction is 'Duelist's Heart and Harem'. It has a really interesting OC who gets involved with multiple characters in a unique way. The duels are well - written and the interactions within the harem are both fun and full of character development.
Another concept is the exploration of new relationships between OCs and the canon characters. Maybe an OC forms an unlikely friendship with a character like Jaden, and through this relationship, they both grow and learn new things about dueling and themselves. It can lead to some really heartwarming or intense storylines.
One idea could be a female OC who is a transfer student to Duel Academy. She has a unique deck based on mythical creatures from her hometown. She quickly catches the attention of Jaden and his friends with her dueling skills and mysterious past.