@goatsarah the endless guilt-tripping is their most powerful tool. Covert Ns are really insidious because they present themselves as shy, introverted, morally superior and even sweet, initially. They're masters at mental gymnastics.
Playing the victim, endlessly talking about themselves and constantly complaining are my three N red flags.
Do you have any advice on how to detect (covert) Ns before they can do much harm? Any specific behaviours to watch out for?