The Essential Guide to Eragon Mary-Sue

She was the perfect Dragon Rider
On her face was never a frown
But she appeared like a disgusting spider
When sanity came around

Chapter One: Mary-Sue Types

Mary-Sue Elven
The typical Mary-Sue. She's beautiful, with raven hair, sparkling sapphire eyes, and a curvy figure. She is kind, sweet, generous, yadda yadda yadda. All the wonderful qualities everyone wants. She has powerful magic and can attempt astonishing feats without breaking a sweat.
Common? Quite.
Romances? Eragon.
Tragic past? Sometimes, but rarely.
Will she die? A tragic death, if at all.

Mary-Sue Varden
Her village attacked by Urgals, forcing her to flee to the Varden! She fights alongside the men, because of course she's not afraid of war! She's stoic, battle-hardened; she doesn't stand for any nonsense! People look up to her for guidance, and everyone loves her.
Common? Not as much as Elven.
Romances? Eragon, Murtagh, Vanir (EW…)
Tragic past? Can you read?
Will she die? Oh yeah, most of the time, shot by a stray arrow after defeating the leader of the enemy army. Everyone will cry and a hero's funeral will ensue.

Mary-Sue Wanderer
Eragon leapt up, sword in hand, as a strange girl approached. She was lean, and carried a large bow in her hand…
Yes, Mary-Sue is a wanderer. Her family was tragically killed, her home destroyed. She taught herself how to make a bow, after finding a 'natural talent'
(translation: she shot an Urgal fifty feet away on her first try) at shooting. She hunts, she fights, and she wins! She knows battle tactics, even though she's never been in a battle before. But why should that be any handicap? After all, this is Mary-Sue!
Common? Kind of…no not really.
Romances? Eragon, Murtagh.
Tragic past? No shit.
Will she die? Occasionally. Maybe after an Urgal raid.

Mary-Sue Princess
Quite possibly one of the most-used plots ever, next to Mary-Sue earthling. Galbatorix has somehow managed to have a daughter. Stunningly attractive, she runs away from Uru'baen because she has never been 'free.' Then she somehow meets up with Eragon, and they go off and have many adventures together. Often she will have been best friends with Murtagh.
Common? Yes, very.
Romances? Eragon (never gets a break, does he?); usually she and Murtagh are just friends, although occasionally he comes into play.
Tragic past? She's a princess in Uru'baen, you tell me.
Will she die? Never.

Mary-Sue Evil
She works for Galbatorix secretly, while pretending to be with Eragon and the Varden. She has managed to get past anyone who looks into her mind, because she can shield her mind stronger than anything. Her ultimate goal is to assassinate Eragon/Nasuada/Ajihad and reveal the Varden's plans the Galbatorix. Her seductive charm enables her to get anyone out of her way. She will do anything to carry out her orders, even if it means doing the down-and-dirty or killing someone. Of course she will kill without hesitation. She is beautiful, which goes without saying. Any weapon will work. There are a few times when she will turn to the good side, but this is rare.
Common? Not as much, but there are a few floating around.
Romances? Technically no, because she's never actually in love with the ones she seduces. If she goes good, it will be because she has fallen in love with Eragon against her will.
Tragic Past? Galbatorix will tell her the Varden killed her people; he actually did it.
Will she die? Depends. Maybe she will be killed because she is found out, and will have a tragic execution. Or she'll jump in front of Eragon to stop Galby from killing him.

Mary-Sue Earthling
The single-most commonly used character. A girl from Earth, and sometimes her friend, gets transported to Alagaesia via book/jewel/magic talisman/bright flash of light. She instantly knows everything that happens, because she read the book. She can speak the ancient language perfectly. Sometimes she will even use magic. She can annoy the hell out of everyone and not get executed, because she is Mary-Sue Earthling!
Common? Extremely so.
Romances? None, usually. Surprising, huh?
Tragic past? Nope.
Will she die? Oh, never. Remember, she belongs to another world!

Mary-Sue Dwarvish
This is not even a category. Nobody ever writes Mary-Sue Dwarvish.