@Vathekvoid
That seems... Extremely specific.
Are you sure you can't write a story like that yourself? I don't know... Maybe it would be interesting...?
Although I write many stories with the SI and Isekai genres, those are just tags in the end because each of the characters I write has their own personalities and stories. I try my best to differentiate my stories from the canon and make my characters follow their own path, which is why I don't usually write stories involving Y/N or using the Reader Insert tag.
I've written two stories that involve Mimic not betraying the Diamond Cutters; one of them is "No Need for a Redemption," which is on this same platform, and I wrote another one called "An Unworthy Redemption" on the AO3 and SpaceBattles platforms.
In "An Unworthy Redemption," Mimic still betrays the Diamond Cutters... But not of his own free will. You'll understand if you read it, I won't give any spoilers.
I don't dismiss your idea as a bad suggestion; it's just not in my writing area.