I would start at the beginning - before you get in too deeply. There is never a reason to be unkind to them (or anyone you are dating). And you don’t need to play games with others to understand whether they are right for you. Their lives are hard enough. But you also don’t have to let anyone treat you badly either.
If I could go back to the beginning of my dating a narcissist I would pay more attention to how I feel. He pushed hard. He controlled the pace of the relationship - and it went fast. I remember feeling numb because it all felt too good to be true. Instead of asking questions, I went along. I was almost high on how good it felt. Maya Angelou says that a toxic person will blow on you to anesthetize you, bite you and then blow again before you notice the pain. I remember thinking of that quote when he first started showing his true colors. I still didn’t run because I thought the bite would pass and that loving, amazing person would come back. If I could go back to that time, I would have slowed things down. I would try to get to know him better before my feelings became overwhelming. I would listen to my own instincts regardless of what it looked like on the outside. I think by not letting him control things, he would have exited quickly. And, since I would not have been emotionally invested, I would have gladly waved goodbye. Try being a little difficult and see what he/she does with it. Change plans. Disagree with their opinion. A great person will be intrigued. If they overreact, you will know that this person is problematic and not right for you. Send them happily off to their next person and clear the decks for your RIGHT person.