Establishing Character Moment/Web Original

"Codex: So, it's uh Friday night, and...still jobless, yay. I haven't left the house in a week. My therapist, uh, broke up with me. Oh yeah, there's a, there's a Gnome Warlock in my living room, sleeping on my couch."
 * Sarah's Stick'Em Up prank in the Lonelygirl15 episode "Crazy Emo Chick".
 * Simon Wood's first scene on the island in Survival of the Fittest sets up his central theme: coming close to succeeding then falling at the final hurdle.
 * Captain Hammer in Doctor Horribles Sing Along Blog has one of these every single time he's on camera! Almost as if Joss Whedon wanted to really hammer home the point about what a creep he is...
 * Most of the main characters in the Whateley Universe get them:
 * Chaka starts off as a young black teenager sharing a room with his unpleasant older brother, and turning into a pretty girl...turning into a mutant...having to leave home and go to a Super-Hero School...and he's thrilled to death about every bit of it.
 * The headmistress, Dr. Elizabeth Carson, gives the welcome speech and immediately comes across as someone you'd better not cross. Then later on, at Halloween, we meet her other identity, Lady Astarte, and we find out she's really someone you shouldn't tick off.
 * Trevor James Goodkind is the White Prince, heir to billions in a wealthy anti-mutant business family and being groomed to be one of the Goodkinds who takes over the reins of power. We first see him and his family at dinner, being waited on, having a staff of chefs, and Trevor is plotting about how, when he grows up, he's going to get his favorite chef to come with him when he moves out. The next morning, he manifests as a mutant and things rapidly go downhill from there, with a series of Break the Haughty scenes.
 * The first episode of The Guild is just a long string of these for each of the characters, first establishing Codex with her weblog:

"Tom: Thank you, Zack, for ruining the 20th take. Zack: You're welcome, man. Tom: You're not sorry, are you? Zack: Nope."
 * Mecha Sonic's first appearance in Super Mario Bros Z involved him vaporizing a poor Goomba at point blank range to retrieve a Chaos Emerald. And that's probably the nicest thing he's done in the entire series so far.
 * Zack from Echo Chamber gets his before the opening credits roll on Episode 1:

"Hi, I'm your Nostalgia Chick, and I, like most of the world, am an American.""
 * Even though she's much more developed now, The Nostalgia Chick's massive ego was seeded with her very first line:


 * Likewise, The Nostalgia Critic's Sad Clown-ness started with him being Driven to Suicide at a dumb song in Cartoon All-Stars to the Rescue.