Well, they could start by sharing their unique experiences. Maybe Chrom has some heroic tales from battles, and Robin can contribute with their strategic insights. They can combine these elements to create a story full of adventure and wisdom.
For Fe, you can develop the character by showing their backstory. Maybe they had a tough childhood which made them strong - willed. In the fanfic, have Fe make decisions that are based on their past experiences. For Chrom, emphasize his leadership skills. Let him take charge in difficult situations and show how his decisions affect the group. As for Olivia, show her kindness. Have her be the one who always tries to resolve conflicts within the group in a gentle way.
You can start by searching on popular fanfic websites like Archive of Our Own (AO3). Just type in 'Robin x Chrom' in the search bar and you'll get a list of relevant fanfics. Another option is FanFiction.net. They also have a large collection of fan - created works.
To write their character interaction, start with showing their initial differences. Supergirl is from a world of superpowers and Chrom from a more medieval - style world perhaps. Have them misunderstand each other's motives at first. For example, Supergirl's quick actions might seem rash to Chrom, and Chrom's more methodical approach might seem slow to Supergirl.
Since I don't have much information on what exactly 'chrom orange' refers to in the context of fanfic, it could be a very niche piece of fan - made literature. It might be that Chrom is a new or relatively unknown character in a particular fandom, and the writer of the fanfic has decided to incorporate the color orange as a symbol, or it could be related to an orange - colored object that is important to Chrom's story in the fanfic. For example, if Chrom is a hero, the orange could be the color of his magic sword or his shield.
There's a fanfic called 'Chrom and Lucina: The Unseen Journey'. This one focuses on their journey together. It shows how they support each other in battles and in making difficult decisions. The author does a great job of creating a believable and immersive world for them.
You can start by searching on popular fanfiction websites like Archive of Our Own. Just type in 'm robin x chrom' in the search bar, and it will show you a list of relevant fanfictions.
I'm not sure specifically what the 'chrom best wife story' is. It could be a very personal or a very specific story within a certain community or family that I'm not familiar with.
I haven't heard of any specifically popular 'chrom orange fanfic' stories. It might be a very specific or new concept that hasn't gained widespread popularity yet.