Exclusive to the second series of Adventures from Moominvalley, she came to Moominvalley to give her brother, Mr. Hemulen, a surprise visit, only to be sidetracked by a group of children with no adult supervision.
Infamous for a clip on YouTube of her most rude moment in the episode, Aunt Hemulen isn't actually such a terrible person, she just happens to be an extremely naggy person who has amazing cooking skills and a genuine care for these children she's never seen before. She has an extreme fear of the Groke and yet she took the hint when the children used that against her and let them be, only to speak of them very kindly to her brother and be saved by them when nearly drowning in the river.
Nana's Fiance
Not much is known about him besides being Mr. Hemulen's nephew, but we do know he had a disrespect for fireworks before his uncle taught him The Way. He seems like a fine gentleman, engaged to a pretty girl who became exhausted looking for him.
Alright so here's a monstrosity of a conspiracy board that I mocked up because I had this thought for a long while. Before we get into a deconstruction of this weird web of adaptation, let's start with the most basic of clarifications to get everyone on the same page;
From left to right, top to bottom, the characters are;
The Hemulen (Moominpappa's orphanage principal), the Hemulen('s) Aunt [both from the book Exploits of Moominpappa/Moominpappa's Memoirs]
The Orphanage Principal, Aunt Jane, Aunt Hemulen [all from the 90s series {Aunt Jane originated from the comics but I used a 90s screenshot here}]
Mrs. Fillyjonk, Moominpappa [screenshotted from the 90s series, this version of Mrs. Fillyjonk is taken from the comics while Moominpappa was in the franchise from the start but who really needs clarification on these 2]
Is that fairly clear? Anyway, let's move onto the characters that started this mess, the 2 hemulens on top of this odd family tree:
The Hemulen and Her(?) Aunt
Ah, these two, the Orphanage Principal and Hemulen Aunt, I'll be calling them the OP and the HA for short.
I've had people mix these two up or think they're the same person when the whole joke is that Moomin did the same thing and got punched in his pride for doing so (she says she's the Hemulen's Aunt, given the context of the OP being called simply the Hemulen we can assume she's the Hemulen HA is referring to, but since there are like 9 other "the Hemulen"s it's hard to tell). So to make it extremely clear;
The OP is a hemulen who took care of an orphanage (purely for Moomin children) and was into astrology, she found a child Moominpappa in a grocery bag wrapped in newspaper at the doorstep of the orphanage she built herself and was really into astrology so she looked up at the stars and got a prediction that he's over talented and such, being a Leo. She named the kids after numbers in order of their arrival, naming our Moomin protagonist Number 13 because he was the 13th, she tied a tag to his tail with the number so she wouldn't get him mixed up. She's a terrible caretaker to the child, not really letting him be a child and getting annoyed at his constant questions and literally said "dreams are trash" right to this child's face as he was talking about an honestly pretty boring dream of disobedience. The rest of her orphanage was supposedly obedient and would avoid Number 13 and his weird way of thinking and asking. Last we now of her is that Number 13 left a note announcing his departure. Moomin still calls her auntie despite all this.
Her orphanage is square and beer brown in color, it's located in a treeless landscape near the sea. She had a symmetrical vegetable garden and a hammock nearby.
The HA is a different story, she was chased by the Groke and was rescued by Moomin when she fell into a kettle of Irish stew that Muddler accidentally dropped into the water earlier. When she came onboard she went to clean the jam-filled deck and the Oshun Oxtra knew immediately that she was going to be very unpleasant, Hodgkins even snuck into the pilot-house of the boat to avoid her. She took it upon herself to become the crew's "caretaker" as her "hemulic duty" and everybody disliked it. At 6 I'm clock in the next morning she was extremely cheerful and suggested things like a sock-darning contest (because she checked their drawers and the implication is that most of the socks had holes in them. Bad crew, bad >:( ) and educational games. When she asked what they're having for breakfast Muddler says they're having black coffee, to which HA snaps back with the suggestion of porridge because "coffee is for the old and shaky" and said the crew's parents would weep if they saw them drinking coffee, but of course the whole crew's parents aren't there one way or another. The crew lament the themselves about the HA being annoying and then she gets kidnapped by a flock of Niblings. The crew thinks she's dead or atleast is having her nose eaten off, then later at Muddler's wedding it's revealed that she became the Nibling Queen and happily teaching the Niblings all sorts of things like writing, sadly she couldn't go to the wedding in person but she sent a portrait of herself adorned with jewels on the frame.
In summary; the Orphanage Principal is a doggess of a caretaker atleast to those who don't abide by her standards of obedience. The Hemulen Aunt is a preschool teacher who doesn't mesh well with a group of male sailors.
Aunt Jane
And then by chronological order in the franchise, we have Aunt Jane! I'll be speaking of her more generally rather than make a more or less detailed summary of her role in the story since she makes more than one appearance in the comics and 90s series (if you want an ultra detailed summary/analysis of Jane purely based on her debut episode in the 90s series, I recommend reading this, while it was made before the original poster watched the 90s season 2 episodes, it still holds up well)
So anyway Aunt Jane as we know her as the rich aunt with a cranky attitude first appeared in the second ever Moomin comic strip storyline; Moomin and Family Life. She was introduced as an antagonist type figure after the Moominparents left to the cave to enjoy some semblance of adventure, she arrived at Moominhouse to complain about the box of swear words they sent her as a prank for her general mean attitude toward them but of course they weren't there, she gets scammed by Sniff a couple times by getting trapped and having to pay for her freedom, in the end of the comic she finally finds Moominpappa and accuses him of being a thief and stuff, Moominpappa lies about the reason he sent the swear box saying it was all in good fun and that he's fond of her, Jane cries because nobody told her they're fond of her in ages and they have drinks.
It's unclear if "Aunt" Jane is referring to an actual relation or if it's a polite pet name like "Uncle" Muskrat in the books, especially when taking the Hemulen Aunt comparison into account.
Comparing her to the Moomins; she seems to more resemble the way Tove drew Hemulens at the time (pictured at the top) rather than the Moomins, see the longer limbs and snout, and the glasses which are (or were?) an extremely common trait among Hemulens, aswell as the lack of hair and hat wearing like the OP and HA from before.
Of course despite this, Lars chose to interpret her as biologically related to the Moomins, Moominpappa specifically, while making comic strips with her in his run of the comics, even giving her a second grand nephew named Wispy (who isn't a moomin at all but we can assume some interspecies relationships went on in his branch of the family tree)
This lead to Aunt Jane fully transitioning into a confirmed paternal aunt of Moominpappa's in the 90s series, and also turning her into an actual Moomin rather than being a dubious Hemulen.
As for links with the Hemulen Aunt; You can see the visual similarities I've illustrated in the beginning of this section, but there's also other things to note. Her role as the unpleasant older lady with some form of authority and some tie to Moominpappa is there, but also when the HA became the Nibling Queen she seemed to have become rich as hell as illustrated by the bejeweled portrait frame sent by her for Muddler wedding (perhaps the Nibling's cave was rich with gems and thus by becoming queen the HA herself became rich).
Summary; Aunt Jane is trans confirmed and she became a millionairess by becoming the Nibling Queen. (Joke)
The Fillyjonk Orphanage Principal
Next we have a very... Original, interpretation of the OP. She's vaguely implied to be related to Mrs. Fillyjonk in some way since Moominpappa uses the same language with her as he did with Joxter, M Fuddler and Mymble's Daughter ("(S)he was just like _").
She's a vague overview of the Orphanage Principal, taking in child Moominpappa when she found him at her doorstep in a shopping bag and naming him Number 13 (but instead of using a tail tag she draws the number on his back [how weird is that??]), being generally a nuisance and strict. She also runs a diverse orphanage rather than one purely for Moomins.
Later she replaces the Hemulen Aunt, being saved by Moomin by jumping in Fuddler's tin while the Groke was chasing her, and really being alot more annoyingly strict and prim than the HA in the book. She also gets kidnapped by Niblings but we never hear from her again, so RIP her I guess.
Summary; Pretty lady, ugly attitude, role thief.
Aunt Hemulen
Lastly, we have Madam Hemulen, or Aunt Hemulen as she prefers to be called. Sister of Mr. Hemulen (yes, Mr. philatelist-turned-botanist Hemulen), she's what you'd call a... Conservative, having more traditional values but ultimately means well in her efforts and is surprisingly forgiving and nice.
Her connection to the Hemulen Aunt is a weird one, they have no real connection nor did the HA ever get hinted at or referenced (as in AH never mentions an aunt or whatever) but they do serve a very specific role; being a self-assigned caretaker of the main characters and bothering them with ~terrible~ things like chores and judgement when they were expecting a carefree time. Also they're both hemulens who have umbrellas and wear dresses. There's this weird connection they both have; the HA got chased by a Groke before being saved by young Moominpappa in a river, meanwhile AH has a strong phobia of the Groke and gets saved from being drowned in a river.
To be honest it's pretty weird adaptationally, like sure it's one thing to have stories and characters be changed and applied to different characters when making an adaptation (the 90s series does this almost everytime it's not an original storyline) but it's another thing to do... This. I'm far from complaining though, I love Aunt Hemulen and it gives us a pretty good lens as to what Mr. Hemulen's backstory could be.
Summary; Misguided in the way she handles being a babysitter because of the way she was raised but honestly pretty kind and caring otherwise.
Conclusion
This is why the Hemulen Aunt is Envy in the Fullmetal Alchemist Brotherhood x Moomin AU lmao. This is a very strange family tree of strict ladies and it's weird how the 90s series handled adapting 2 or 3 characters, but it managed to make all of these ladies unique in their own right with varying degrees of likeability or interesting-ness. It's fun to imagine putting them in the same room and watching what would happen.