Thief Guide
Thieves are jerks. Not a bad thing, especially if they're being a jerk to someone who deserves it. They like to paint themselves a independent rebels, But their actions are surprsingly group oriented. It's no fun being subversive if nobody's around to watch. Thief friendships are bonds forged in fire, and handshakes laced with blood. Go through enough with one and they will die for you, although they'd never admit it.
The problem with thiefs is that their antics are inevitably going to get someone hurt. Someone who doesn't deserve it. Most classes would give up, but thieves double down. After all, gambling might as well be a sure thing when you're betting on yourself. Sometimes, they do manage to pull a victory out of this cycle. But most of the time, they need another class to deliver a reality check.
Aradia beating up Vriska within an inch of her life was a long time coming.
A thieves outward aggresion as a defense mechanism. Nobody can get close enough to hurt them if they don't let anyone in. As a general rule, they see any expression of emotion or genuine kindness as a sign of weakness. Of course, people can still get close to them, if they're persistant enough and wear down these barriers. Although these people can still leave, when they realize the thief is a jerk all the way down, further reinforcing2 the need for barriers.
As a result of these barriers, thieves aren't able to express themselves in a healthy way. The instict to filter everything through a layer of outward aggresion makes it hard for them to articulate positive emotions. This is especially true in terms of romantic attachment. Thieves don't really vibe with heartfelt confessions, or dramatic proposals. It makes them too vulnerable, too uncomfortable, putting their heart in the hands of someone else. This makes their expressions of romantic intent come across more like bullying.
Did you ever know a boy in grade school who would pick on girls that he had a crush on? Hell, the inverse also exists, especially in anime. Vriska and Tav are a fine example. Vriska couldn't just ask him out, she had to set up this elaborate Pupa Pan/fairy roleplay to court him. That scene reads as her making fun of him, if you don't understand how thieves work. She even paralyzed him, so he would have no way of escaping, just like a spider. Even so, he rejected her, and the barriers of outward aggresion went right back up.
Thieves typically come from families that don't make them feel appreciated. They develop their high drive and ego from this, constantly pushing for bigger and bigger accomplishments to make their families appraciate them. When this doesn't work, they keep trying, hoping that bigger accomplishments will work - which is how that aforementioned "doubling down" pattern develops. At the end of the day, they want to feel loved and be praised for their accomplishments - despite how much they push people away.
It's really sad, seeing this pattern develop. These people who just want to be loved, and praised for their accomplishments, pushing everyone away because they're afraid of being hurt.
Prospit Thieves
The whole "antisocial but group oritented" aspect of thieves is strongest in prospits. The "mean girl" archetype has it's roots here. The people who take over social circles, and rule with an iron fist.
Vriska isn't really a good example of an average prospit thief. I think Asuka from Evangelion is more grounded. She's absolutely a jerk, but people still hang out with her, and she's fairly popular.
Derse Thieves
Derse thiefs have a lot more aimless aggresion. Every response is dripped with sarcasm, in mean and cruel ways. The outward aggresion is more intense, the walls are built much higher. You never know if they actually like you, even more so than prospits.
Meenah trying to kill anyone who entered her dream bubble on sight is exaggarated, but only slightly. I've known a few, and the way they talk is always the same. Every response is some variation of "No, fuck you."
Closing Thoughts
It's hard to get close to a thief. It's a lot like petting a porcupine. You need to be careful and gentle, and even if you are, you might get hurt anyway. It's just the nature of the beast. Be kind, respect their boundaries, and don't expect any compliments. If they decide they like you, you'll have someone you can rob a bank with. If they decide they hate you, you will know.
If you are a thief, I could give you advice on how to live your life, but you wouldn't take it. At the end of the day, you're just going to do what you want, damn the consequences, damn what anyone else thinks. I'm not here to pass judgement, just don't be surprised when someone else pushes back, or when people have trouble interpreting your weird courting rituals. Bullying the people you like isn't going to get you anywhere. Start being a jerk to people who deserve it, and you'll go far.