I'm sure you know what I mean- and it's not just the habit of creating self-insert Mary Sue girlfriends, either. I've seen people who literally think they know exactly how a particular character thinks and feels, despite all evidence to the contrary, and believe that they're the only authorities on the subject, and speak for the character in a way that no one else can- not even the creators.
(Personally, I prefer a "what-you-see-is-what-you-get" approach, and I only invent new traits based on inference- not for the sake of using the character as a mouthpiece.)
A milder but not necessarily less irritating form is when a fan will be disappointed with a decision the creators made concerning a character they supposedly "admire", and go on to claim that their version is the "correct" version. Not only is this extremely arrogant, but it's also an insult to the creators- it implies that the creators don't know the characters best. By extension, this is also a denial of who the character really is, canonically and artistically, because they prefer a derived ersatz character.
So I don't believe that these people are really "fans" at all. They're fans of their version of the story.
So it particularly irks me to see "fans" of Oswald the Lucky Rabbit, most of whom weren't aware of his existence before Epic Mickey came out, don't want Ortensia to exist. It mostly surprises me that they even bothered to find out more about the character, much less learn that his girlfriend used to be a rabbit.
I first learned about Oswald through the Disney books that my parents used to own- so I've known of his existence since before I can remember, although like most I never saw any of his cartoons- just some drawings- simply because they weren't available.
So when I learned that Disney had bought back Oswald from Universal and was going to put out a Disney Treasures set, I was excited by the prospects of it all. We bought the set as soon as we could...
Admittedly, I didn't care for the decision to make his girlfriend into a cat either. It simply made more sense to me to make the two of them rabbits, and I liked the way she was drawn and animated better. I think it's perfectly okay to be unhappy with a decision an artist makes, and regard it as a mistake that could've been done better- but it's not okay to claim that you have made the "correct" version. Nobody but the artists who work for the people who own the copyrights of these characters have the authority.
This isn't to say that you can't write fanfiction. I'm just a bit of a stickler for canonical continuity, and I don't like it when it's disregarded for one's own ends.
Here's how I feel about Ortensia: If Walt Disney himself decided to make Oswald's girlfriend a cat, then so be it- if you wanna argue about it, bring Walt back from the dead and tell him off. Maybe I do prefer that she be a rabbit, but you don't exactly see me changing Scrooge McDuck into a mean and nasty Christmas-hater just because that was what he was originally like.
I figure that's how Warren Spector felt about it too. Walt made her a cat, and that was how it was when he made his final cartoon before Oswald was taken away from him. Heck, Walter Lantz kept her that way.
In fact, I don't even know if Ortensia and the rabbit are separate characters! Most people interpret it that way, but I've yet to find any reliable source stating whether Oswald dumped the rabbit and hooked up with Ortensia, or if Ortensia simply changed her species- that what I thought when I first saw the cartoons. That happens sometimes, y'know. Pegleg Pete, for instance, was originally a bear, then a dog, and finally a cat after he was paired with Mickey.
UPDATE: I've found conclusive evidence that Ortensia is, in fact, a simply renamed and "respecied" Fanny.
First of all, according to the DisneyWiki, Oswald's rabbit girlfriend was definitely named Fanny, citing the book Walt in Wonderland: The Silent Films of Walt Disney. It isn't just a rumored fan name, like I previously suspected.
Also (and I don't blame fans for missing this), Ramapith: David Gerstein's Prehistoric Pop Culture Blog has provided the soundtrack to the Lantz-era Oswald short "Bowery Bimboes" here: http://ramapithblog.blogspot.com/2010/09/lucky-new-oswald-finds.html
Currently, the actual visuals that go with these sounds are lost.
I've listened to it, and the voice that's clearly meant to be Oswald says "Hi there, Fanny." As we all know, Oswald's girlfriend had become a cat. And this short refers to her as "Fanny"! So Ortensia is simply her new name, and Fanny isn't a separate character.
(On a side note: In the short "Spooks", Ortensia/Fanny is referred to as "Kitty". Not that it makes much difference.)
Hopefully, this'll end all the debate. Unfortunately, all the artists who have been drawing Fanny and Ortensia side by side will have wasted their time...
UPDATE 2: Turns out I was wrong about Lantz keeping her a cat. By 1932, beginning with "Carnival Capers" at least, they turned her into a dog for some reason. And she's still referred to as "Kitty". Seems as though she's gone through so many changes that it doesn't really matter what the heck her name is.
UPDATE 3: Things have gotten more confusing- in "Springtime Serenade", Oswald's girlfriend is a rabbit again. So yeah. Ortensia, therefore, is based entirely on Walt's decisions!