That is a really good question and something I’ve spent a lot of time thinking about, as well!
Who is Lusamine?
Even from what we’re given throughout the games storyline a lot is still left vague and up for interpretation.
Was Lusamine a good person who was just negatively affected by Nihilego’s toxins, that are said to bring out people’s innermost desire while crushing all sense of inhibition? Or was she always a narcissistic control freak?