On the occasion that I include myself in a story, I present myself as an Interactive Narrator. Invariably, my characters will blame me for everything bad that happens in these cases, while gleefully ignoring the possibility that I could be a force for good as well. And they also like to point out every single flaw in my technique. When your characters are unwilling to suspend their disbelief, you know something's wrong.
Naturally, I only do this in comedic situations. If I'm trying to write something dramatic or otherwise serious, the fourth wall remains firmly intact.
There was one unreleased story where I tried to insert a version of myself. It originally presented "me" as a powerful member of the lead cast who was later revealed to be an Elite, and a slight revision made "me" the chief of the regional police force as well. Later on, I realized how ridiculous this was, stripped away the police force detail, and tried to rewrite "myself" as a constantly-complaining Scrappy that the readers would want gone—and I then planned on granting their wish by having one of the main villains shoot "me" dead. Afterward, the idea was that the rest of the lead cast would largely forget "I" was even there and just continue on their merry way.
Needless to say, this story went unreleased and unfinished for a reason.
On the topic of putting traits of myself into unrelated characters, that's something I find very difficult to avoid:
- Colin has my short temper and desperate need for companionship (particularly of the female variety).
- Joanie is the embodiment of my desire for a supportive female figure in my life.
- Collie (in her revised form) is my desire/tendency to do random things at random times.
- Annie is what I find physically attractive in a woman, is much smarter than I could ever hope to be and has a talkative Robot Buddy (not quite the parrot I'd kind of like to have, but close).
- Bella is the little sister I've always wanted.
- Jim (though not officially my character) is constantly cheerful and a great tactician, two things I desperately wish I could be.
- Jim's Alakazam is my stubbornness combined with my cynical side and given some measure of authority.
- Wyatt is the personification of my overprotectiveness of people I care about.
- Icira is my evil, somewhat sadistic side combined with playful snarkiness and Genre Savvy. Also embodies my desire to have enough money to effectively do whatever I want—except I'd stay within the law, of course!
So far, the only exception has been Joanie's Bellsprout, Audrey II, who is just a bad ripoff of the plant from Little Shop of Horrors.
In short, no matter what I do, my writing seems to be full of me.