I've been reading a lot about this case lately. It's one of the very worst cases but is also fascinating because of the couple dynamic and the levels of culpability and involvement. I think it's in the middle of Fred & Rose West, and Brady & Hindley in terms of female involvement. Rose West was as bad if not worse than Fred, in no way was she forced or roped into it or anything. Rose was the dominant partner of the two and she was also very into women/girls moreso than men IMO. Hindley is a monster not defending her but I do think she was manipulated into it, even Ian Brady's portrayal of things depicts it that way and he's trying to spite Myra with everything he says. It's no excuse that's not what i'm saying here, what I mean is I really don't think she'd have did anything like what she did if she never met Ian and I don't think she got as much out of it as Rose or Karla. Karla's not quite as bad as Rose I don't think she'd have committed serious crimes without Paul, however she was very into it and got a lot out of it clearly. She was a pedo, there's zero doubt about it and i'm not just talking about in the sense that she committed sex crimes against underage girls thus she is a pedo I mean that independent of Paul she was sexually attracted to young girls. There's also something very unique in this case IMO because I think the murders largely happened because of Karla and I also think she cared less about killing the victims than Paul. I'll expand below as I can see people taking that the wrong way, i'm not saying she was worse than Paul or Paul had a moral objection to murder that's absolutely not what it was and that's what makes it unique IMO.
The attacks that Karla was most into were the drugging and raping underage girl attacks clearly, exactly what happened to her sister. Karla knew a girl known as Jane (a pseudonym I believe because she was underage) when the girl was 12, Karla worked in an animal clinic and Jane volunteered there because she loved animals so much. She loved Karla and looked up to her however Karla quit (she was about to be fired because she was suspected of stealing Halothane which she absolutely did since she used it in all of these attacks) and they lost contact. Then three years later when the girl was 15 Karla randomly phoned her, the girl was shocked but overjoyed. She went to the area Karla and Paul was living to hang out with her and stay with her overnight. They had a great day, went shopping, watched a movie, etc. Jane had a great time then at night Karla offered her alcohol and next thing she knows she's waking up and it's morning, she feels sick and Paul is there, they are meeting for the first time. Of course Karla drugged her and they raped her. However the crazy thing is this was all entirely Karla's doing (not the rape obviously), Paul had no idea any of it was happening he never even knew who Jane was. It was Karla's demented surprise "wedding gift" for Paul. She did all this on a day Paul wasn't around without telling him then when Jane was unconscious she called him and told him he needs to get home right away she has a surprise for him. IMO it was a "gift" to Karla herself as much as Paul since she was a paedophile and wanted to do it herself.
They did this a few times to Jane and they almost killed her the same way as Tammy one night. Jane stopped breathing one night, they phoned an ambulance but then quickly called back and cancelled it when they got her breathing, they then both stayed up with her all night to make sure she didn't stop breathing again. The insane thing is Paul was the one who said no more drugs, he banned Karla from using Halcion or Halathane. Later they had another girl they were grooming (again someone Karla knew who Paul didn't, Karla brought her up when she randomly came to mind) her name was Norma. Thankfully Norma wasn't responding to Paul's advances and when he was complaining about it Karla kept telling him she could have her "out like a light" if he just says the word. He kept refusing until he got so pissed that he beat Karla so she would stop trying to entice him to drug their victims. That's unreal, Karla killed her sister this way, almost killed another girl she knew, and yet she seemingly desperately wanted to do it again to another girl she knew. Karla seemed way more okay with death to me than Paul. Again not because Paul had any moral objection but because it ruined his fantasy, they were both demented and were perfect for each other in the worst way possible. I'll leave out all the stuff regarding Paul's obsession with Tammy and how "devastated" he was after her death as this will be too long already and i'm sure most are familiar with it, but it's bonechilling and shows just how much he wanted his victims alive because he felt he owned them. If they weren't attacking unconscious victims then they had to be conscious and this is where IMO Karla largely instigated the murders. Tammy was the only death to someone who was drugged unconscious which is why I've not included her here, she's the same situation as Jane except they managed to get Jane breathing again.
Of the three deaths they caused, Paul and Karla only actually premeditated one murder Kristen French. It's he said/she said who instigated it or whether it was both, however IMO the murder part was Karla considering the context. Something extremely telling to me is Paul's complete lack of concern about being identified until the attacks with Karla, Leslie Mahaffy with the blindfold is the only time he tries in any way to avoid identification and I don't think it's a coincidence that's the first time he and Karla attacked a conscious victim together. Even further Paul's concern about identification is clearly completely about Karla since he abducted Leslie without a mask, he only blindfolded her to take her to Karla. Anyway we'll get back to Leslie's attack but lets look at Paul's other attacks. Paul never wore a mask during any of the Scarsboro Rapist attacks or in any of the rapes he did on his own after them, in fact I fully believe that was part of his fantasy. Paul wanted his victims remembering his face and thinking of him all the time, implanting memories of the rape in their mind forever was clearly part of it that's why he made them say "I Love You" and "Merry Christmas" over and over again so when they said those things they would think of him. He didn't want them thinking of a dude in a mask he wanted them to see his face, even after he was freaked out by the sketch looking like him he raped women without a mask. I think the fantasy overpowered his common sense/self-preservation.
So now Leslie Mahaffy, this was not planned it was just horrible luck. Paul just happened to be in the area walking past iirc he was there connected to his cigarette smuggling and he saw Leslie walking towards her home. Paul thought to himself he could peep on her so walked towards the house, however what he didn't know was Leslie was locked out of the house (which her mother gets way too much hate for, the circumstances seem to be misreported everywhere) and didn't want to ring the doorbell because her mother would go nuts. She was likely checking to see if a window or something had been left open so she could get inside. So when Paul walked up to the house Leslie walked back and they bumped into each other. She asked what he was doing there, he said he was looking for a house and must be in the wrong place. She explained what happened, he said you should just ring the doorbell, she said she can't she just needs to find a place to stay. Heartbreakingly I think she was so desperate that she was hinting to him to allow her to stay with him, this might not be true since it comes from Paul/Karla but he claims when he said she could stay with him she got super happy and started skipping around. I actually find that believable and it makes it so much worse as when they got inside his car he pulled a knife and told her to put a blindfold on.
Karla was surprised by Leslie like I said it wasn't planned, Paul just appeared with her blindfolded. Right up to the very end Leslie was blindfolded, they decided to kill her after it slipped off. Karla didn't say a word around Leslie, clearly because she was concerned with identification unlike Paul. However very tellingly she wanted to participate so she whispered in Paul's ear a lot, she gave Paul questions to ask Leslie that weren't important questions they were purely about the fantasy and her being their victim showing how much Karla was into it. She also told Paul to tell Leslie to do things to her sexually, again showing how into it she was and this wasn't just about Paul as is often portrayed.
Now consider the complete difference between Karla and Paul regarding identification, then the next attack they do together is Kristen French. It's the only time Paul planned out the murder of someone and it's with Karla who is the one concerned about identification. It's the only time Karla procures a stranger victim for Paul and not someone she knows and drugs. Karla approaches Kristen and asks her for directions then when they are looking at a map Paul appears behind Kristen with a knife. They always knew they were going to kill her which is why they didn't blindfold her or didn't try to hide their identities in any way, Paul even called Karla by name. IMO it was clearly Karla, she was annoyed with the way Leslie went and wanted a full scenario like that where she can participate but she's concerned about identification unlike Paul so the only way she'll participate is if they kill the victim. To be very clear this is in no way defending Paul he was a monster, I just don't think that was Paul's fantasy he wanted victims alive. He wanted the strangers thinking about him, and he wanted those he knew in the same kind of relationship as he had with Karla, by which I mean eventually consensual after grooming and abuse that was clearly his plan with Tammy and it's what he tried with Jane and Norma before they thankfully noped out. Not because he cares about consent but because he wanted to "own them" like he felt he did Karla. He was devastated by Tammy's death much more than Karla and was utterly obsessed with her, they had pictures of Tammy all over their house and that was Paul's doing not Karla and he mentioned Tammy constantly to Jane and mentioned how she looked like her while he was grooming and abusing her. Murder was not his thing, however Karla was a pedo who wanted to rape underage girls and her concern about being identified meant they had to kill them. If this isn't convincing enough regarding Karla's paedophilia Karla literally says on video to Kristen "I like little girls" while she is sexually abusing her.