I dm a couple of snowflake players and two classic style antiheroes.

I'll start with the worst offender, the Utlrasnowflake. While it's not uncommon for people to use RPGs as a form of wish fulfillment, Utlrasnowflake rarely breaks his established form more than superficially. Of noble or noble-esque lineage, has a powerful and/or once powerful family (usually as merchants). Is the black sheep of the family. It seeking to build their own empire, sometimes literally other times analogously. Will ALWAYS play a social/charisma character, mixed with the most potent fighting or magic combination they can swing, but usually they stick with social/charisma.

As a player he likes to do his own things, rarely caring about the party's mission, and has often put the party in danger for the sake of his character's personal interests. He also has delusions of eloquence and decorum, but in truth acts inappropriately in many circumstances; like ignoring noble hierarchy and cutting off a higher ranking noble, a princess (another player) to voice their own ambitions within a very conservative foreign court .

The second snowflake, Dietsnowflake is not as bad and has gotten better after I explained what he was doing. He took Utlrasnowflake's habit of playing the same character in different names and basically dropped the pretense. He played the descendants of his original character, giving them all his traits and his last name. Not so bad? Except his original character was making babies in every possible universe. From a homebrew D&D campaign to Dragonlance to Eberron to Ravenloft to Providence Rhode Island. I understood that Dietsnowflake had an attachment to the character, but it was getting annoying.

Now for the two classic style antiheroes, the worst is actually my brother, whom always plays the same character. Stoic, gruff, with little empathy or emotional depth to his character. Often shrugging off horrific scenes as just another Tuesday despite his background as a tailor. He ignores threats made by scary NPC, Monster or allies alike. And often just becomes a bit a wall flower character that is tooled for combat (he's a bit of munchkin).

The second classic style antihero is actually worse in my opinion. He's been RPing since the mid 80s, and when the mood hits him has come up with some of the very best moments in our gaming group. But his characters are often monotone in terms of personality. They are flat line until he thinks of something clever and then suddenly they come alive. It's frustrating because I have to experiment with content to find something that will bring him to life, because it's glorious when it happens.

Oh, and then there's me. I love to torture my DMs and GMs with outlandish characters. An badass Dwarf cleric tooled for combat, but is obsessed with butterflies, having a good collection of them fluttering around his beard at all times (they're tethered to individual strains of hair). His starmetal armour has intricate designs of butterflies, flowers and grassy fields. The thing is, he does not talk about butterflies, and will ignore all inquires about them.

Then there was my half-orc barbarian that a played because I'd never played a half-orc barbarian. Gronknor, whom wore a tiny little loin cloth that was about 6 sizes too small. This was to mess with one of the other players that had acted a little homophobic in a previous campaign and I was relentlessly teasing him with Gronknor. The dick jokes were plentiful, but surprisingly subtle. Unfortunately Gronknor met his end cutting a new loin cloth from the Incarnation of Death's room separating curtains.