You can start by looking on fanfiction.net. It has a large collection of fanfics from various fandoms, including ones related to Wally West and Artemis. Just use the search bar and type in their names to see what comes up.
There's a fanfic titled 'Wally West and Artemis: Partners in Time'. In this, the story could be set in an alternate timeline. They are forced to work together to fix the timeline that has been disrupted. Their relationship evolves as they face various challenges together, with some really emotional moments when they think they might lose each other.
Well, it could change in many ways. Firstly, they would have a deeper emotional bond. The fact that they are going to be parents would make them more committed to each other. They would start having conversations about their future as a family, like where they want to raise the child. Also, Artemis might become more dependent on Wally during the pregnancy, especially if she has any physical discomforts or limitations. And Wally would be more than happy to take care of her. Their relationship would shift from just being partners in crime - fighting to partners in building a family.
Well, I really like the fanfic 'Wally West: Racing Against Time'. It's a thrilling read as it pits Wally against a new and powerful enemy that can manipulate time, which creates a whole new set of challenges for him. Then there's 'Wally West and the Lost Speed Force'. This one is more of an emotional journey as Wally tries to find his connection to the speed force again. And don't forget 'Wally West's Allies and Adversaries' which gives great insights into the characters he interacts with.
Another plot could involve their cultural differences, if any, in the fanfiction. For example, how they celebrate different holidays or traditions and how that affects their married life. They might have to find a balance between their own heritages and create new family traditions.
Their superhero friends could be main supporting characters. For instance, Dick Grayson might offer advice on how to balance married life with superhero work, given his own experiences.
Often, there's the theme of adventure. Writers like to put them in exciting situations together, like fighting against a new super - villain or exploring a strange part of the DC universe. And there's also the theme of loyalty. They are shown to be loyal to each other in many fanfics, no matter what challenges they face.
Wally could use his super speed to be there for the reader instantly whenever they're feeling the urge to self - harm. His presence alone might be a deterrent.
I'm not familiar with the exact 'artemis and wally proposal fanfic'. However, if it's a fanfic about a proposal, it may include elements like how they first met and the journey of their relationship until the point of the proposal. Maybe there are some sweet moments, some challenges they overcame together, and finally Wally getting down on one knee to ask Artemis to marry him.