My second and current wife had her son young. She's 39 and he's 20. I'm 46 and my kids are grown and out of the house. We got married about 3 years ago, so I'm not exactly a father figure in his life, which is good because he's kind of a d-bag.
He may be a cocky jerk, but you can't take away his athletic ability and the girls it attracts. He plays baseball at our local junior college and is being recruited by one of the top college baseball programs in the nation. As such, he's always got some hot, blonde, wannabe Instagram influencer hanging off of him. A couple of them even had OF accounts that I found. They never last very long, he has his fun and move to the next one. He knew I liked checking these girls out whenever he brings them around. He tries to use them to his advantage, asking for things in front of them so I won't look like a jerk and say no.
One time he really wanted to borrow my new Range Rover for his weekend trip with his GF and buddies. They're about as responsible as he is so the answer was no, all three times he asked. He must've really wanted to use the Range Rover because the next thing I know, his current girlfriend, Bree, is bouncing around our house in skimpy shorts and a t-shirt with no bra. Fortunately for me, my wife was at work, so I could freely appreciate this girl's beauty.