There's nothing concerning at all about her history, character or personality. Nothing.
It's not just a case of "well we don't know everything about her childhood or adult life". No we don't and we could theorise but that's with no external evidence whatsoever. No GP/CAMHS/MH/Police/CYPSS/Medical/training/ employment records at all.
The prosecution would have had access to that and came up with nothing.
The defence if they saw fit, could have presented her as having a mental illness which even if it didn't absolve her of responsibility, could be a mitigating factor. They didn't.
She was first arrested and her arrest in the news was years ago.
Nobody came forward with anything concerning. Because if they did, it would have been included in the prosecution case. Every other medical serial killer case has had a wealth of red flags and people coming forward to the Police to report their experiences and that was presented in court and witnesses called as part of the prosecution case.
There was ample opportunity for anyone who felt they had significant information or even just their experience of her to report that given the vast timescale between her arrest and trial.
And we're not just relying on people coming forward. Numerous people were interviewed by the Police during their investigation. People she did their nursing training with her and lived with in nursing accommodation, numerous ex and current colleagues, mentors and managers and parents of infants that Lucy Letby had cared of.
Not one person gave any indication of anything particularly odd or suspicious about her. Literally no-one.
Apart from one manager and colleague I think who thought it was weird LL wanted to work with the most unwell babies. Which LL defence presented a very good explanation for.
Even the consultants who accused her could come up with nothing unusual, odd or suspicious about her.
That doesn't mean she's innocent but it does mean, as the forensic psychologists have said, that if she's guilty, she is an unprecedented anomaly that would represent a complete overhaul of the previous theories and understanding of medical serial killers.
Which could of course be the case and I'm not excluding that possibility.