I would say red flag strait away with the chit chat.
I had a client who was super clingy from the first day we met, he poured his heart out to me after doing the deed, told me he had tried to take his own life and started crying whilst holding onto me
took me ages to calm him down. Then he wrote me a 2 page a4 letter posted it through the letterbox saying how we could be 'great friends' and could i help him 'make friends'.
I couldn't see him again after that as he was just too unstable, left me feeling quite sorry for him
xx