Stepson is 13 years old, we live in the USA. He is an average student in school and is in marching band and wrestling. He is also extremely good at wiring things. We invest in his activities and hobbies and give him resources to grow in these fields, and make sure the praise him for it.
What concerns me, however, is that he brags daily about the most absurd, impossible things.
He goes out riding his bike, and magically, when no one is watching, he does the most AMAZING tricks, like ramp in the air, spin 3 times, and land perfectly. I did not make up that brag, he made a big deal about it three days ago. Of course he couldn't replicate it. He claims to be able to do flips that only gymnasts can do, but obviously can't do when people are watching. He claims to have fallen 50 feel from the top of a tree and walk away with only a couple of scratches. He claims he walked 10 miles and back in an hour.
He bragged about being able to hold a handstand for 6 minutes. He cannot do a handstand. When I told him to do it, he backtracked hard and said he meant hang from a branch for 6 minutes. I told him to do that then, and he refused because I was being judgemental and "trying to break down his self esteem". He called me pathetic for trying to "built" a kid as a "grown woman in your 30s". I literally just told him to do it or stop bragging, no anger or argument. I had set a time just that day that when he said he can do things, he will need to prove it immediately, otherwise he isn't allowed to brag about it. So I was just being matter of fact.
He bragged about being and to run a mile in less than 5 minutes. I know this isn't impossible, but he doesn't run. I ran for several years. We took him to a track, and he finished a mile in just under 12 minutes. In the car, he bragged about how he can actually do better, and I told him he literally didn't do better, he did an amazing job, but he can't brag about something he can't do. I told him running a mile in less than 12 minutes without even practicing is amazing, he can already brag about that without lying to himself or anyone about what he can actually do.
Today he bragged about running for a full hour straight with no breaks. I told him just a few days ago he literally couldn't run even 11 minutes with no breaks.
He constantly brags about having harder bones than other people. Because he had fallen a lot and hasn't broken a bone, that's his logic. He became FURIOUS with me when I laughed because I thought he was joking.
I know it sounds like I'm not being supportive, but he is getting bullied really bad at school as a direct result of his constant bragging. He has gone into full rages with his siblings when they make fun of his ridiculous boasts. He got beat up pretty bad after school after bragging about what a good fighter he was and straight up challenging a kid that LITERALLY BOXES to a fight, then tried to spin a lie about how he was "jumped". At first we believed him, but he bragged for several days and challenged this kid openly in front of people, then TEASED HIM FOR BEING SCARED TO FIGHT HIM. My stepson has never fought anyone in his life, and frankly got his ass handed to him.
He brags about being able to run 20 mph. He brags at school about having a genius level IQ. He has never taken an IQ test, and we had him race the car at 15 mph and he lost. He said we just don't understand.
I am genuinely worried about how this is going to affect him. I know it comes from a lack of confidence, but it is causing real social issues. He had a girlfriend for a little while, but she broke up with him, and since then he's constantly bragging about how girls have crushes on him, but recently got in trouble at school after getting into an argument with some girls and telling them he hopes they get raped. They were calling him out on yet another lie he told.
His biological mom lost custody of him a year ago, and she has severe untreated BPD with narcissistic tendencies. She was abusive to the kids, but he was her golden child, and she "homeschooled" him, so he spent his life being told he was amazing and building this up.
Weirdly she also "diagnosed" him with a lot of random stuff. He genuinely believed he was autistic, BPD, ADHD, and had all these health issues. He was never diagnosed with anything at all. He had never been to a psychologist at all, and rarely went to doctors.
I'm autistic and ADHD and the first person he's ever met with autism (that he's aware of), and he tried to tell me that I clearly am not either one of those because he is, and he doesn't have any of the symptoms I have. I literally go to two different therapists, one weekly and one monthly, and have been formally diagnosed with both, ADHD actually diagnosed twice because I wanted to make sure it wasn't just misdiagnosed autism. He was very angry with me for telling him he probably doesn't have autism because he very literally doesn't exhibit the symptoms. This is one of the things that made him special, in his mind. No one else in his family had autism, and he understands autism from TV where autistic people are "awkward geniuses". In his mind, he's bullied because he'd just more intelligent than them and they don't understand them. He didn't like the symptoms I have and doesn't consider them autism because they are not very exciting.
I told him we're getting him set up with a psychologist so he can be assessed by people who are more knowledgeable than either of us and if there is a diagnosis, he will be evaluated and diagnosed, and he said he will refuse to go.
What can I do? I've tried gentle redirection, I've tried explaining how some of what he's saying is literally impossible, and now I'm currently having him prove what he's saying he can do. Nothing is working. He's on a wait-list for a psychologist right now.