I'm having an issue with someone like this. When I was a kid he took advantage of my naive honesty and used it against people we both knew. He would start off asking me a known answer question which I would answer happily. He understood that I was very socially isolated and thus appreciated any conversation, even if it was just answering obvious things. Looking back on it I'm embarrassed I didn't see how patronizing it was. Regrettably I'm quick to trust and this would build a temporary rapport with me. He might even get me to laugh.
Once he can see that I'm in a noticeably elevated mood, he strikes. He'll ask a real question that he genuinely wants to know, wait a bit gauging my reaction. If it appears to not go well with me he'll appear to let it go and follow up quickly with one to three diversionary filler statements about unrelated things. Usually things that would evaluate to truth or something I can't argue with. He then repeats starting from the known answer question forward until he gets what he wants or, if he's upset with me for not giving him what he wants he'll bother me in a unique way.
He knows I have pretty horrible social anxiety and will instigate a long awkward silence. Usually when he's interrogating me we're somewhere I can't easily escape him or would appear upset had I left. If we're in the car for example he'll turn off the radio, close the windows and we sit in silence. He knows if one of us talks again it relieves the pressure I'm feeling and leverages this to induce word vomit which he'll happily pick through to get what he wants. Some days he's particularly crafty and all of his known answer questions lean towards the genre of the topic he's interested in.
Long story short: I'm very suspicious of people who show interest in me or what I do outside of a professional relationship. Even people who at first appear empathetic and courteous will turn right around and use everything you gave them against you if they feel slighted. Some people are just wolves, able to pick up on our naivety and use it for their gain or to hurt us.