Hi hello I love this ship So Hecking Much it is underrated because of most likely the physical age difference thing WHICH IS CHAOTIC EVIL AND C H E A P so I destroyed it and did my own thing because their love is more powerful than making each other old platonic ladies. I HAD TO DO IT.  
Fact remaining that if you’re gonna have her story be about giving away her beauty and leave her OLD NOT UGLY without even really mentioning the fact that she Ages™ in the dialogue of the episode than boy howdy am I gonna take creative liberties with it BONCH.  
I seriously wish it got more attention than it does but I guess to the untrained eye it is PRETTY WEIRD HOW OLD MISTMANE LOOKS IN CANON
 
Few days ago I asked for opinions on how I should go about Mistmane’s design and got feedback mainly leaning toward doing a Kirin-esque thing with it SO I DID.  
My main fear with it was making her seem too pretty which I probably did anyway but I think the bigger takeaway from their story should be the ideal of it being ugly rather than in actuality I guess.  
So I went with the idea of ponies still being racist at the time and everyone being immediately turned off from her in their Kirin states.  
Eastern dragons are wiggly noodles anyway so it fits her weird celestial hair haha
 
Few things I changed about the designs specifically:  
-Obviously instead of rapid aging for a magical misfortune I turned it into more of a species change thing. ‘Cause being old doesn’t necessarily make you ugly and it really bothered me about the story. OTHER THAN THAT MISTMANE IS ONE OF MY FAVORITE CHARACTERS.  
-Sable Spirit weirdly has an eye color change from purple to teal when she’s under her messed up spell which I used and applied to both her and Mistmane. Consequentially even though Sable Spirit is back to being herself again, her eyes remain that same blue instead of the original purple. In Mistmane’s case I had her go from blue to green. (Mainly I wanted to dissociate Sable’s design away from Scootaloo’s as much as physically possible)  
-I think I ended up using a comic image of Mistmane for her color reference and with Sable Spirit I just used the lineart and darker color for the mane, I liked the contrast in color more.
 
About the ship itself:  
-I headcanon Sable definitely had a crush on Mistmane very early on seeing as they were best friends, I think Mistmane unknowingly made Sable feel a little useless at times seeing as how perfect she was at everything  
-Mistmane was also completely oblivious to Sable Spirit’s affection, most likely having known each other from a very young age and grew up very close together  
-Sable was never truly that good at magic, often times struggling to keep up with Mistmane, but maintaining it all the same. With that I think a lot of her spells would end up backfiring on her, thus why in an attempt to not only become more beautiful like the friend she envied, but also obtain a significant increase in magic, her makeshift spell ends up transforming her into a beast  
-I think she’d be super self conscious about it and probably cry to herself before revealing what she looked like to the other townsponies, all of which would be appalled or outright disgusted at her new appearance. None of which made her feel any better about her situation, but angry and frustrated, causing her to lash out with her newfound abilities and lack of temper  
-In the episode it says that Sable Spirit took to power by force, I think that in my verse she gained a significant increase in power in her Kirin form and overtook it that way rather than something dirtier like sabotage or murder >>; Sable seems too much of a pushover to do anything bad to that degree, she might have gotten a little angry and rampant though. Still I think she was in line for the throne but perhaps the next available heir was a child or something so they let her take it after she threatened to harm the foal.  
-She’s definitely a bad ruler in the sense of how poorly she treated her subjects. I’m keeping that she wanted to make her palace beautiful above anything else, she probably had always had an eye for it but was undervalued or something. I figure their land is relatively peaceful so she’d never have had to deal with battles and whatnot.  
-When Mistmane reversed the spell on Sable Spirit, Sable fell head over hooves for her best friend  
-Mistmane didn’t stay very long after returning to save Sable that first time back, but Sable thanked her relentlessly and bared significant guilt for what her friend had done for her at that point  
-Their encounters with each other would be on and off for long periods of time, Mistmane having most likely met the Pillars during her travels away  
-Not sure when exactly their relationship would change into a romantic one, but I do think it was a gradual process of time allowing for Sable Spirit to not only accept the fact that Mistmane had forgiven her long ago, but that she needed to forgive her self in addition to it  
-Sable Spirit had always found Mistmane attractive in her Kirin form from the moment she first saw her in it, something that took Mistmane a while to believe and even comprehend  
-Mistmane was significantly more capable of maintaining her composure in her new state of being in comparison to Sable Spirit  
-Sable having been a Kirin before Mistmane, helps her sometimes with the odd habits she finds herself to be experiencing; cravings for meat and scale shedding being some of them  
-The two got into a habit of bidding farewell by promising each other’s return to one another  
-When the threat of the Pony of Shadows looms over, Mistmane again promises Sable that she will return for her, but her promise is broken when her and the Pillars seal him along with themselves within Limbo  
-Heartbroken but hopeful, Sable Spirit would often times revisit the place in which Mistmane was last mentioned to have been seen  
-In a desperate attempt to retrieve whatever she could of Mistmane, Sable managed to give herself a child made of the two of them from a scale of Mistmane’s she had held onto for a long time  
-Sable has a son that she names Tā De Xīn or Her Heart, mainly just referred to as Xīn  
-In the future, Mistmane doesn’t find out she had a son for a very long time, it’s until she meets one of her descendants from her son’s lineage that she realizes what Sable had done, to which she is relieved Sable had managed to find some sort of peace without her being there  
-Mistmane continues to cary buried guilt about having abandoned Sable past the point of her death, but lives knowing she moved on in her own sense of it
 
I’m hopefully intending on doing pieces like this with all or most of my ships, it’ll kinda help me set up baselines for going into the actual Next Gens.  
But also with that Art Fight starts tomorrow which I’ll most likely prioritize for the time being. unu