I played with a guy that fell into both categories. He was always researching obscure ways to power up his character or cheat death. This went on for two years and he constantly fooled the other players into thinking he was making new characters, but NOPE! It was his bloody drow bard in disguise, stealing the loot and ditching the adventure when discovered!
He made it to level 14 in D&D 2nd edition using this tactic.

I could see that being legit though if he passed enough bluff and disguise checks. Dick thing to do but that's role playing.

He didn't need to. No one ever called him out on it for some reason.
But I eventually got him.
Him and I happened to be the best players at the table; we played smart and were willing to take risks, so the DM loved us. Since I was going to be moving away soon, he offered to write a mini adventure for our two favourite characters. He, of course, picked his drow, Sylph, because it was technically his only character. I picked my halfling rogue, Pip.
The quest revolved around the drow's back story of wanting to overthrow a demon queen, Lolth. I happened to have an old halfling barbarian who was captured by her years ago with another group so I made it my job to rescue him. Into the Abyss we went, gathered an army of demon's, located the queen and rushed off to fight her. But Lolth is a lover of treachery and our whole army was really working for her.
So, Sylph and Pip were standing before a demon queen alone. The drow player saw this as the end and, being a good friend, asked me out of character if I wanted to do one last charge for glory. I said yes. We rolled initiative and I went first.
I casted Hold Person on Sylph.
Then, I offered to execute this nuisance to the demon queen in exchange for my barbarian.
The drow player, completely blindsided as I play exclusively good guys, is fuming.
The DM this this is hilarious, agrees, and I walk out of that hellscape with two characters.

I'm a little late to the party but that sounds great.
I don't get why she didn't kill you too though, since you were kinda right in front of her.
Was she less, "kill everyone ever" evil and more "I rule by whatever gets the job done" and sometimea goodish evil.

She thought the betrayal, built up with a straight face and no clue over a period of two adventures (and several real life weeks) was too good to not reward.
Sylph and his player completely trusted me and and Pip, and suspected nothing because they always felt invincible. They had an escape plan for anything an adventure might thrown at them. He never considered another player fighting him with anything but brute force. And then I killed his character with him unable to fight back.
Lolth, lore wise, loves that stuff, and my plan actually banked heavily on it.

Ooh, I love it when a betrayal is more reliant on lore than just mechanics. Nice job.
Also that completely makes sense now, I never bother to learn deities or royalties in, well, anything.
Games, books, movies. I just get to confused.
I have a small story about that that kinda emphasizes that but it doesn't have the most satisfying ending.

Let's hear it so I can spread the legend.

Also, one of my friends that reads a lot usually makes fun of me for forgetting really easy character names and remembering the names that sound funny or are super long.
Like l'll forget King George, Lord Sally and Prince Greg, because all they do is talk about things while advancing the plot, even if it is super interesting to me.
But I remember Durine, Slartibartfast, and Algernon simply because the a sentence like "And Durine slashed at the air in front of him, daring the goblin to come closer." will stick in my mind.

What I'm trying to say is, I'll usually remember and appreciate both characters and their contributions, but unless they shoot a thing or almost die for some reason, their name is Mudd to me.

It's not really about a game, its about my failure to recognize characters.
Here we go I guess.
I read the walking dead comics but I'm only up to number 8 or 9 because they are expensive. Im a fan of big old physical copies and I buy the chapters.
My friends watch the walking dead on TV, and I don't and have almost no idea what's going on at any given time in the series.
So there is a character, I dont remember his name so I'll call him Rick Grimes.
Im absolutely positive it wasn't the actual Rick, because Rick is Rick and even I can see that. but lets call him Rick Grimes to prevent spoilers.
So one night we are watching the show and I ask my friends who this character is and they say it's Rick and too shut up and watch.
I say, " I don't remember Rick, where did they first meet him." And they tell me where and I instantly recognize him.

In a moment of pure genius I blurt out.
"Oh that Rick, the one that dies in the comic!"
My friends flip their **** and pause the episode just to yell at me.
When they finally calm down, I bring up the several points.
1. The show doesn't follow the comics.
2. Rick died when they went to "Germany", and since they are already in " Spain" now which happened after "Germany" and he is still alive they probably chose not to kill him at all.
3. I mean, come on, how often do they actual kill main characters.
To point three they quickly responded with "All the time! Have you even seen the show?" I admitted that I hadn't.
They were right though, in the comic Rick died pretty cheaply. And it's not like I read the walking dead for the baddass survivalists.
I felt like an asshole so I shut up for the rest of the episode.

But I wasn't free yet.
During that particular episode,(and later in the ones to follow) Rick almost dies more than anyone I've ever seen in a show. 5 times is what I remember.
I don't just mean like he jokingly "played" with a zombie or pranked someone in his group pretending to be dead. I mean he had the most dangerous zombies at his throat and barely held then away by inches. Or worse, he would get surrounded and there would be a dramatic stall to attract attention to how screwed he was.

And every ******* time he almost died, my friends turned to me and said "Thanks a lot asshole, you killed Rick!"

For anyone who has seen the show and is wondering, I totally forgot which character it actually was, and I sure as **** don't remember which episode we were watching. I also don't even care if they are still alive. I'm too embarrassed to check.
It might be pretty obvious if you read the comics though. Might be, Its been a while since I read them myself but you know.