Man... I headcanon NiGHTS is autistic, and seeing it from that perspective makes it a WHOLE lot worse - being seen as a "failure" because they were seen as "different". On top of that idk how old NiGHTS is, but I think they're pretty young compared to the other Nightmaren, so having that pressure just because they happened to be a first-level is no doubt gonna scar them for life.
Actually you could also make the point that Jackle is likely disabled as well; being a "failed" first-level and all. Assuming he came before the twins, I wonder if he had it even WORSE off.
Makes me wanna write a fic where NiGHTS' new friends (Sonic and Ristar especially) and family (Illumina and Ariem) find a way to deal with Nightmare once and for all. Problem is that killing Wizeman also kills NiGHTS.