How To Spot Self-Inserting Roleplayers

The players get upset or agitated when their characters don't get what they want. This is one of the biggest and surest tip-offs you're dealing with a self-inserter. And even if the character isn't a proper self-insert, you still likely don't want to play with this kind of person because at the very least, you're probably looking at a parasitic roleplayer.

They can't handle their characters looking bad. Maybe they get upset or agitated when players or other characters point out that their characters haven't exactly been great people. Or perhaps they insist that storylines be retconned so that their characters weren't actually at fault (EG, "let's just say it was an evil duplicate, okay?") or so that the frowned-upon actions never happened in the first place. This is the other biggest and surest tip-off.

They take their characters way too seriously. Must everything about their characters always be super-dramatic, important, deep, or special; or do they act as if it must be perceived this way? Are they incapable of poking fun at their characters or letting their characters be the subject of humor in some way? Are they incapable of admitting when their characters are being silly or ridiculous? There might be some self-insertion going on.

They can't admit anything is their characters' responsibilities. For example, they insist that nothing is their characters' faults (even when it undeniably is). Or even if they do admit that their characters behaved ridiculously or unfairly, they don't actually think it's on their characters to actually do anything about their behaviors, but instead just expect everyone else to be more patient/understanding/forgiving.

There's little to no variety between their characters. Especially in their personalities - their characters have virtually identical desires, insecurities, flaws, and virtues. And if it goes so far that someone's characters are all basically the same person with different names slapped on, you're very likely looking at a self-insert player. Players whose characters are all nigh-identical to each other are most likely just playing themselves.

The canon characters they play are wildly OOC. If the canon characters they play have done a 180 somewhere (EG, suddenly loving something or someone they vehemently hated in canon, or are suddenly bothered by something they were completely chill with in canon), or if they follow hobbies or passions they were never shown to have in canon to the exclusion of their canon hobbies or passions (EG, someone who canonically loves working in an aquarium suddenly ditching it all to become a chef, rather than simply, say, learning to cook on the side), or if any other defining traits or characteristics have simply just vanished, you might be looking at self-insertion.

They say they can't play canon characters without changing them in some major way. Deliberately making AU versions of characters who are substantially different from the original versions is a perfectly valid choice, but players who say they absolutely cannot play canon characters without drastically changing them probably just can't play anyone besides themselves.

They say they have to play OCs because they can't play any canon characters. Of course, there's nothing wrong with choosing an OC over a canon character out of personal preference. Also, players who are fairly new to a fandom might not know everyone well enough to really get a handle on any of them. And if there's little to no variety between the characters, they may not be able to find anyone they can really get a bead on. However, if they say that they absolutely can't play canon characters despite being very familiar with the canon materials and despite there being a wide variety of personalities among the characters, you might be looking at the same problem above - they just can't play anyone besides themselves.

Their characters' backstories or intended arcs are changeling fantasies. For example, finding out they're long-lost children of canon characters and henceforth going to live with them, being adopted by canon characters, or even simply just leaving their horrible biological families to find a "real" family among the canon characters. This often indicates they're trying to play out a personal wish-fulfillment fantasy.

The players fish for relationships that make no sense. Despite their characters being the last people anyone would want to get into a relationship with, they try to get them into relationships regardless. Or they fish for relationships with characters who would most likely be looking for someone very different as a long-term partner. Or the plots they want to play out require that canon characters go entirely out of their ways and/or put their lives and ambitions on hold to be with their characters.

The characters' tastes and opinions are inordinately closer to what their players would like than what they probably should like. Now, it's important to note: just because a character has a few traits in common with the player, does not automatically mean it's a self-insert. (In fact, it can be good to give a character a trait or two in common with yourself, and it's not a great idea to play a character who has tastes and views you know absolutely nothing about.) But if you find, say, a thousand-year-old demon prince who follows fashion trends followed by the player's age group, doesn't watch, read, play, or listen to anything that the player isn't a big fan of, and has the same moral and/or religious/eschatological views as the player despite growing up in a very different time and place, you might be looking at a self-insert.