Well now I have! I added a post on my neocities, but here's the copy/paste below.

The most basic shit about Mashmorgan is: Mash and Morgan spent a long time together. So long that Mash starts considering herself a part of the Fairy Calendar over the Queen's calendar (see: Totrot having to remind her "you're not the only one who remained, you're the one who is going home! You were never meant to be here in the first place.") Furthermore, Mash and Tonelico didn't just hang out. They were good fucking friends! Tonelico trusted Mash enough to tell her that Tonelico is, in fact, a ball of rage and ressentment wrapped in a savior skin (which is a big deal considering Tonelico lies to Fucking Everyone about her true feelings on things.) It's important to note that the ONLY time Morgan ever smiles during the entire lostbelt is with Mash ("Sure! We did our best, didn't we?" while sending Mash home.)

Speaking of, the fact that Tonelico sent Mash back in the present at all is very telling of Tonelico's feelings for Mash. The excuse she gives Totrot is "well I wanna recruit Mash later," but that's very obviously bull; Tonelico's last conversation with Mash makes it very clear that Tonelico expects them to be enemies later on. Besides, how can you recruit someone you know for a fact you won't remember? Morgan has zero reasons to send Mash back to her own time. She knows she's shooting herself in the foot by doing that. She KNOWS that Mash will turn out to be an enemy. But she's sending Mash back anyways. Because it's the right thing to do? Because it wouldn't be fair otherwise, and Morgan values fairness above all? Because Tonelico failed to save Uther, but she could still help one friend on this bitch of an earth? You tell me.

Now that's our basis to read Mash and Tonelico as exes, or people who pined for one another, or just very close besties, whatever you want. Which means we've now a wonderfully tragic romance (or friendship if that's your thing, but I feel like romance makes it tasties) of two people who do love each other but cannot stand by the same side because of widely differing ideals. Adding to that the dramatic irony of Mash and Morgan never knowing each other at the same time- Tonelico knows who Mash is, Mash doesn't know who Tonelico is. Mash knows who Morgan is, Morgan doesn't know who Mash is.

Mash still holds Tonelico's memory close to her heart- Tonelico (the summonable one) has a line mentioning that though she has no idea who Mash is, Mash keeps looking at her with sadness. Furthermore, while Morgan changed a lot from her Tonelico days, Mash still knows the woman pretty well- when asked if she's willing to fight, she responds "well yeah I know the gal she won't give up without a fight."

Obviously, Morgan doesn't remember Mash. But she still holds the knight in high regards; in the Fairy Cup event, she mentions that "oh lol you guys had Mash with you no wonder you guys turned out fine." Additionally, when you barge in her throne room early lb6.2 to ask her about Mash, Morgan does not remember that name, but she does react to the description of Fairy Knight Galahad. She doesn't remember Mash, but even without her memories something still echoes in her about it.

So that's all our canon basis to go wild. What are the roads we can explore with this ship then?

For Tonelico/Mash, there is obviously a "doomed romance" angle. Whether they're lovers who can't go anywhere, or people pining unwilling to start something at all, the fact is: this romance is doomed, and they both know it. They're from different worlds and times. Mash going home implies Tonelico's failure. This love cannot change anything, but it mattered that it was here.

For Mash/Morgan in lb6, there's the "lovers to enemies" angle. As I said before, they're clearly both still fond of each other on some level. But that's not enough. They both stand on either side of that war, because they each want to protect different things. The agony! The pain! Delicious. Of course, the most tragic part of this is that Mash didn't even get to kill Morgan herself. All of this, and they never got the catharsis of battle at the end. (I should add that I'm a firm believer of the inherent eroticism of homicide.)

Less obvious, but an aspect of their dynamic that I find really interesting is that... Mash is someone who is constantly asked by various nonhuman people for understanding. Goetia, the Lion King, Beryl, all asked Mash to understand their pov and goals. Because Mash, as a homunculus, fundamentally stands at the edge between human and nonhuman. She's legitimately these people's best shot at being understood. But through this pattern, Morgan is noticeably the one person who never asks for understanding. She explains herself, but that's it. What she does ask of Mash, however, is to find a good reason to fight Morgan. Cuz Tonelico just endured 3000 years of the most senseless and brutal violence- she’s just fresh out witnessing her attempt to save Britain being destroyed on a whim. The only thing Tonelico asks is for their fight to actually have meaning for once. Don’t face me just because I’m mildly inconvenient to you. Face me because you are striving for your own star. That, I will respect, and should you succeed in defeating me- I will be fine with that. (Also because Morgan long gave up on being understood, so she's not even trying with Mash, which is why I think it fucks that despite Morgan being a fucking brick wall, Mash still manages to know this girl better than most.)

Post-lb6, on Mash's side, this ship is a case of "this girl I used to love changed a fuckton, but also She's Still Here." On Morgan's side it's "I do not know who you are, but my body does remember you and it's fucking weird." And both these things are haunted by the ghost of "Oh christ we fucking killed each other. We can never go back to who we used to be. How do we build a new relationship after All This Shit? What if she forgives me? What if she doesn't?"

Additionally. Morgan is someone who fundamentally believes herself to be evil. That's why she's always like "ohh I'm a wretched witch I do this because I'm selfish teehee." It's a Sakura behavior, she's rationalizing the bad shit happening to her as "well I was evil anyways so I deserve it." Veering into headcanon territory now, but I think Morgan would see Mash as her total opposite, someone who embodies the good in this world- she's fucking fairy knight Galahad, the purest of the round table. So it's also cool to explore Morgan thinking she's unlovable struggling to understand why Mash would be interested in her. Possibly worried about corrupting Mash too, historically things have never turned out well for people close to Morgan.

Ok this is all my thoughts that have actual canon ground. Now back to making shit up. I think Mash should get to be fucking deranged about Morgan. Mash has lost MANY people since the beginning of the story, but that trauma is shared with Guda. Morgan's however is her trauma and hers alone she ain't got no one to relate. I think it would be a great way to showcase her character development, from someone who struggled to understand Mozart's "yeah humans suck but that's why I love them!" to someone who can be incredibly Not Fucking Normal in her grief. AND that means you get neat Beryl parallels as well. Mash sees her own behavior as something reminiscent of Beryl's, and feeling SO bad about it, but what is she supposed to do? She's lost so much so fucking much can't she just have something to hold onto for once? Something more tangible than a memory? Anyways I think Mash should get to mishandle Morgan's corpse SO fucking bad.

Anyways. Say whatever about lb6, but Morgan did successfully save one thing in Fairy Britain. She did successfully save Fairy Knight Galahad.