One way is through character development. Show how Ash's character flaws, like impulsiveness or a lack of communication skills, can lead to him hurting Michael. For instance, he might make hasty decisions without fully understanding the situation, which has negative consequences for her.
Well, it could be a story where Ash's actions are driven by misinformation. Maybe he believes Michael has done something to endanger the crew or a mission, and in his attempt to stop her, he ends up hurting her physically or emotionally. For example, he might accidentally cause her to get injured during a scuffle or say things that deeply wound her.
You can try looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of various fanfictions, and you might be able to find some related to Michael Burnham being hurt. Just use the search function on the site.
One common theme could be her facing physical harm during a dangerous mission. For example, getting injured while exploring an unknown planet or during a battle with an enemy.
A popular 'Ash Tyler Fanfiction' is 'Ash Tyler's Redemption'. It focuses on his journey towards redemption after all the events he has been through. The author does a great job of showing his growth and development as a character.
One possible scenario could be a misunderstanding between Pike and Burnham that leads to emotional hurt. Maybe Pike makes a decision in a mission that Burnham disagrees with strongly, and it causes a rift between them.
By showing the flaws in both characters. For example, Pike might have his own insecurities or biases that lead to him hurting Burnham. Burnham, on the other hand, might have her own expectations that are not met, causing her pain. This can make their relationship more three - dimensional.
Well, it's really subjective. There are many talented writers in the Star Trek fanfiction community. Some popular ones might be those who have a deep understanding of the Star Trek universe and can really capture Ash Tyler's character well. For example, some writers who have been in the fandom for a long time and have written multiple stories about different characters in the Discovery might be good at writing Ash Tyler fanfiction too.
One great Ash Tyler fanfiction could be about his backstory before joining the Discovery. It might explore his training and early experiences in Starfleet. For example, a story could detail how he overcame challenges during his academy days.