Perhaps a time - travel based fanfiction. Christine accidentally gets sent back in time to a period when Doctor Strange was just starting to learn magic. She has to find a way to get back to her own time, and in the process, she ends up changing some events in Strange's past that have unforeseen consequences for their present relationship. Strange has to use his growing magical powers to fix things while also dealing with his feelings for Christine.
A story where Christine is kidnapped by a powerful dark magic user who wants to use her to get to Doctor Strange. Strange has to overcome his own insecurities and fears to rescue her. Along the way, he realizes just how much Christine means to him, and Christine, in captivity, discovers newfound strength within herself and starts to understand Strange's world of magic even more.
Their relationship could be developed in a more comical way. For example, Christine could accidentally keep getting involved in Strange's magical mishaps in a really clumsy yet endearing manner. This would make Strange see her in a new light and bring them closer through shared laughter.
One idea could be a what - if scenario. What if Strange and Christine had a moment of passion during a time - traveling adventure? Maybe they kiss in a parallel universe where they're not bound by the normal rules of their relationship in the main MCU timeline.
There's also a fanfic called 'Love in the Mystic Arts'. This one combines the magical world of Doctor Strange with the relationship between Stephen and Christine. It has some really interesting plot twists where Christine gets involved in the magical realm more than she expected, which adds a whole new layer to their relationship.
Perhaps a fanfiction where Doctor Strange loses his powers and has to rely on his wits and the knowledge of ancient spells he has memorized to defeat a powerful enemy. This would show his growth not just as a sorcerer but as a person. For example, he could use his medical knowledge in combination with some basic magical principles to outsmart the foe.
Reconciliation is another theme. Since Stephen's transformation has changed him so much, there are often stories about how they try to reconcile the old Stephen with the new one, and how Christine comes to terms with the changes in him and their relationship.
One idea could be Doctor Strange accidentally sends the Avengers into an alternate dimension where magic doesn't exist and they have to find a way back using only their non - magical skills. Another could be that an ancient evil forces Doctor Strange to choose between sacrificing the Avengers or the entire world. Or perhaps a spell gone wrong makes the Avengers swap powers with each other, and Doctor Strange has to fix it while also dealing with an incoming threat.
The appeal of Stephen Strange and Christine Palmer fanfiction lies in their complex relationship. In the original stories, there's a lot of unspoken feelings between them. Fanfiction allows writers to explore those feelings more deeply. For example, how Christine deals with Strange's new life as a sorcerer.
One great place to start is Archive of Our Own (AO3). There are numerous well - written fanfictions about Stephen Strange and Christine Palmer there. You can search by tags like 'Stephen Strange/Christine Palmer' and sort by kudos or bookmarks to find popular ones.
One idea could be that they team up to face a new, powerful interdimensional threat that neither can handle alone. Maybe a villain has found a way to merge different dimensions in a chaotic way, and Iron Man's tech and Doctor Strange's magic are needed to stop it.
One idea could be that you insert yourself as a new apprentice to Doctor Strange. You could start with little magical knowledge and learn from him, facing challenges like protecting the Sanctum Santorum from minor demons. Another could be that you are inserted into the story during the time when Strange is facing a powerful enemy and your unique modern - world knowledge helps him in an unexpected way, like using technology to enhance a spell.