Questionable Questing

Jane is a couple years older than her brother, and so she always took the leadership role from him and always kind of put herself in the riskier jobs. Which really caused John to really not only focus on becoming stronger but he was also the one to really focus on a life outside of fighting, in going to school, learning medicine and engineering. With the goal of escaping this life all together.

While futa Jane was about lying, stealing, fighting, and dealing

John didn't want to let his sister down or see her get hurt so he was always the cautious one. The one to suggest smaller jobs or look at more legal options. To keep his mouth shut when a client was provoking them. Jane on the other hand was a lot more aggressive in everything. She needed to be the strongest. She needed to be the baddest bitch and be respected. Or people would hurt her and her brother.

And she grew to like being tough and being respected. To find joy in power and advantage

That's the idea. Jane wants respect and control. John wants to survive and move past it.

How does Jane treat girls and femboys vs John?

Jane's more casual and seemingly paradoxically more accepting. She'll fool around, freely flirt and show anyone who catches her eye her interest, but she usually isn't looking for anything serious and anytime someone pushes for that she usually shuts it down hard. She's very flighty and very touchy on the subject of relationships.

While John makes friends with everyone, he usually takes time to openly talk about how much he cares about someone. He's almost painfully honest, all the time. Since he hates lying more than anything due to his childhood of never knowing how his foster parents felt about him. So while he's very reluctant to say I love you. The minute he does it's for life, he will gladly go into the fire for you.

All for that seduction and sex and easy friends but never stays long

While John takes awhile to open up and is kind of standoffish but once he does, he's your brother for life. Which also neatly goes into the siblings next big difference.

When they got the offer for the navy, John saw it as a second chance. He jumped at the opportunity. He dressed right, he did all the classes, he said yes sir to everybody. On the surface, he was the goody two shoes. The model marine which was title that he would carry with him for a long time.

Although underneath all that was somebody who still liked to pull pranks with his sister and was perfectly willing to get revenge or defend himself. He was just more subtle about it. Which leads to Jane. She didn't like the military. She saw it as an opportunity sure, but in her mind they were just a bigger gang. A gang she needed to not only prove herself in but fight back to show she couldn't be fucked with.

There is no home for Jane. Only jobs and moments of struggle to win

Her home is with John, and she trusts him with everything since he's one of the only people in her life who's never betrayed her, but other than that for Jane to trust someone it would either take years of time spent together or personal sacrifices on their side. Or for her to hold absolute power or control over them.

You could probably guess which one's easier, and why Jane kind of defaults to bullying or pushing everyone around her a lot of the time.

So she has very few close companions she's pushed under her will completely and everyone else leaves her, making her feel betrayed and reinforcing her bad views

That's the idea. Her childhood brings out the worst in her and the best in John. Although John does kind of soften her image a little bit. Since they're practically attached at the hip, a lot of her friends become his and vice versa, and John is often the one who steps in to smooth over after a fight or when there's conflict. As well as stand up to his sister on occasion if she's being a jerk.

Plus while John's issue is honesty. Jane's issue is betrayal and while she will screw people over, she'll never do it to someone she likes or to a coworker on a job. She could hate you, but she'll complete the gig and worry about revenge or justice later. Which again combined with John being a teddy bear and her obvious love for him really helps cover up a lot of her more negative traits on a surface level.

A lot of Jane's big blows up unfortunately for her mentality has been close friends because they are around her enough to see that uglier side and call her out on it. Which like you said really reinforces a lot of those negative traits.

So she doesn't turbo fuck and seduce into sex slaves their friends at the start of the story