ngl, I ship it.  
If I wasn’t working on a bigger project, I’d probs try to write a fic for this. Or maybe I’ll do something.  
Basic idea would be something like  
>cozy spends 12 years petrified  
>time doesn’t pass for her while she’s petrified  
>a few more years pass while Twilight tries to rehabilitate Cozy  
>finally gets her to agree to at least try to fit in  
>flurry is informally tasked with reforming her  
>flurry does manage to get through to her, slowly  
>but for every step cozy takes forward, flurry takes one backwards  
>in the end, they’re both around the same level  
>cozy is still scheming, but tends to do it in a more constructive way  
>flurry becomes a “I decide which rules apply to me” type, but not maliciously