She is interesting because she is a killer?
She's interesting because she's flawed. Like all humans are.
Look (and this goes for the next poster also), I've been one of the strongest critics of Janeway's actions in this episode over the years. She was wrong. Absolutely wrong. Tuvix was a living, breathing sentient being and Tuvok & Neelix's existences ended when they essentially died in a transporter accident. Tuvix did nothing that caused their demise & could not be held responsible for their deaths.
That it appeared Janeway was swayed by Kes's emotional appeal makes it even worse, in my eyes.
But I want the captain to make mistakes sometimes. I don't like perfect heroes.