... um, excuse me, Mary Sue, I can see you're extremely busy being deeply wonderful and charming, but would you mind if I asked you a few quick questions? It'll only take five minutes. Lies, all lies! Okay? Okay.

Okay, so you're beautifully tragic - or tragically beautiful, whichever you prefer! - with your soulful heliotrope orbs and your tumbling silver locks, your curves in all the right places and your Hot Topic wardrobe, and of course your Obligatory Tragic Back Story of Deep Woe And Stuff. You couldn't be more obviously Different and Special if you carried around an illuminated placard reading 'Look At Me, I'm Different And Special!' or everywhere you went you were accompanied by a heavenly choir singing The Different And Special Song. That much I'll give you, though I rather wish I didn't have to.

The problem, however (you knew there was a problem, didn't you?) is this: Is that - the curves in all the right places, the gorgeous hair, the huge yet unspecified tragedy blighting your back story and justifying the look of hidden sorrow in your mesmerizing amethyst occuli - really supposed to be enough to explain why everyone you meet runs away, within moments of exchanging forenames, with the idea that you're a sweet, put-upon young innocent who deserves only love and protection?

Yes: instatrust. One of the most commonly-encountered attributes of the Mary Sue, and among the most obnoxious, is the tendency that they have to be trusted more or less on sight by just about every regular they encounter.

We've all seen it happen. A randomly-placed beautiful girl walks into the canon characters' lives - and within days, sometimes even within hours, she's moved into the spare room they don't actually possess, selected members of the cast (and it's usually the closed-off, emotionally constipated ones at that) are pouring out their entire life stories to her, she's acquired a shiny new love interest and she's well on the way to uncovering just about every skeleton her new best friends have in their particular closet.

It doesn't actually matter how suspicious the characters in question usually are of newcomers, what their reasons for being suspicious might be, or how much might be at stake if they were betrayed.

No. They trust her.

She's just so different.

On the rare occasions, indeed, when a Mary Sue newcomer isn't instantly trusted by all it's normally so that the ficcer can demonize, or at the very least pillory, her detractors for being at best unbelievably unsympathetic: at worst downright evil. How could they be so callous, or so thoughtless, as to insinuate that Serenity Sakura Kath'rynn Sparkle Moonbeam was anything other than a sweet, innocent, put-upon victim of circumstance?

( Further TL;DR Continueth Below. What? I Was Annoyed! )

The regulars don't know her. Consequently, they're going to treat her with the same caution they would any other complete stranger who made the same claims. Yes, including the un-pretty ones. They're not immediately going to let your Sue hang round with them, move into the spare room they probably don't have and vow they'd give their lives to protect her. It's sad that the Sue's in danger but what the Hell's it got to do with the regulars and why should they believe her anyway? She could be deranged. She could be lying. She isn't, but she could be, and until they know for sure she's not they'd most likely want to keep her at arm's length. Mary Sue's angst past doesn't count for much in the face of good, old-fashioned self-preservation.

Your Sue is not the regular cast's new best friend. She's just some girl they've met. They won't buy everything she says just because she's the one saying it. They might feel sorry for her. They might decide to look into what she was telling them. But they would not believe everything she says on a few seconds' acquaintance just because she's the one telling the story. Sorry.