I've never been able to work her out, quite frankly. She is just so incredibly different to any murder/serial killer I've ever read about. She's been compared to Allitt but those comparisons are lazy and completely wrong. They are nothing alike.
She was genuinely and sincerely liked by everyone, as far as I can tell. She was outgoing, sociable and I get the impression that people wanted to be around her. That's not something you can say about almost any other serial killer, as far as I can think of. Shipman was said to be a "lovely man" but when you read about him he was quite the loner and weirdo with few social connections. Few people seemed to actually like him other than his elderly clientele and a lot of people took objection to him.
Perhaps it's the wrong thing to say but I find her absolutely fascinating.
Whereas all I can see in her are the whole array of similarities to other serial killers.
She isn't a unicorn for being sociable. Gacy was far more sociable than Letby ever was. Was very active socially, politically, and in his community. Some compartmentalise well. Gacy was in many ways more like a sociable, connected paederast (which he also was) than a lot of serial killers, but that doesn't mean he wasn't an example of what a serial killer can be.
I think Letby was middling on compartmentalisation. Her whole life revolved around what she did at work. Her house seemed... Soulless, somehow. Like all she did was sleep there, on her dragon hoard of handover sheets. We never really learned anything about real dreams, hobbies, or relationships outside CoC.
She wasn't like one of those killers who have no ability to blend, who drift and kill and end up in trouble on the regular, no. But she wasn't one who had a rich and vibrant life and a growing family and active social life (that wasn't just going out with the girls from work for drinks occasionally) either.
She had friends at work, but she seemed to use them for emotional validation and information on the babies, and would get frosty if they wouldn't respond as she wanted them to. She also had a number of people at work who didn't get on with her, who thought she was a 'madam' and bossy and had an attitude of superiority. I don't know if many of those work colleagues wanted to speak firmly on her behalf at trial... but I think it's telling that no one did.
MOO