I think you can see the difference in the Batfam with their relationship to killing, because there are nuances to it.
Jason Todd: will kill anyone he considers beyond redemption. He kills to save future victims of the bad guys. If you can't stop being a shit stain and no jail can hold you it's bye bye. Also, if killing you is going to make saving others more effective, you are a goner too (depending on where he is in his character arc)
Stephanie Brown: will kill in self defense and also to protect others. If it's between the bad guy and her/someone else, bad guy it is. She's not going to feel bad for it nor overthink it. Obviously it'd be great if there were other options but life sometimes is complicated.
Dick Grayson, Tim Drake and Damian Wayne: will kill to save someone else. In Tim's case there is more rationalization, more indirect. If it's their life they'd rather die than break the rule (Tim is paranoid about turning evil, Damian feels guilty for his previous killing), but they can't stand and watch/not save others, even if the guilt is gonna wreck them.
Cassandra Cain and Bruce Wayne: they don't kill. Period. Unless it's an accident, and they will feel absolutely horrible for it. Dick could also be in this category, but I think if he was in a situation he would kill on instinct because he can't help saving people. It would kill him, but he's just unable to not save others.
*Disclaimer* Obviously up for debate and I don't know some of these characters as well as I should, but here's my take for some of the other Batfam members as well.
Barbara Gordon: I think she could be in the same category as Steph, being a cop's daughter, but I see her landing somewhere in-between Dick, Tim, and Damian, and Cass and Bruce. She'd rather use her intellect and skills to bring whoever to justice and have them face punishment for their crimes. Though if push came to shove, she'd go there, but only as a last resort. And like the others, she'd likely obsess and run scenarios to see if she could've done it differently and without killing.
Harper Row: I think she follows the same general code as Babs, but has a bit of a harder edge to her at times. She's lived in injustice and had an abusive and absent father. She's fiercely protective of her brother and those she cares about, so yeah, she'd go there, but would prefer not to. She wanted to kill Cass for the death of her mother, but realized that it wasn't Cass's fault. Not really. She's inspired by Cass to not kill, but I think if pushed hard enough she would.
Kate Kane: She's a military brat and former soldier, so I see her somewhere between Jason and Steph, but probably closer toward Steph on the spectrum. Killing is likely not something she feels good about, but if it's "for the greater good" and/or for justice, then she accepts it as part of the job.
Helena Bertinelli: Like Kate, her family background ties into her views on killing. She's seen death and seen how corrupt people wield power and death for the sake of control in the mob/mafia world. But since she's seen the darker side of it as opposed to war like Kate, she leans more toward Jason's POV. Though she realizes it's a never ending cycle as someone else will just rise up to fill the power vacuum when it comes to the mob world.
Duke Thomas: I'd say he has the most varied view on killing, but he's probably in the mix with Dick, Tim, and Damian. Though he may swing toward Steph or Harper on one end of the spectrum or toward Cass and Bruce on the other end, depending on the situation.
