DS has always told pointless lies from quite a young age but I thought as he matured he would grow out of it, however he seems to be getting worse and more and more manipulative too.
He lies about usual stuff like it wasn't him that did something and will blame his younger brothers, lie about getting a shower or doing homework etc. but he's also started lying about things that are such obvious and pointless lies that I'm starting to think he's a pathological liar. An example from today; I had a migraine and could smell really strong lynx coming from DS's room. I came down and asked why he was spraying so much (I wasnt angry at all) and he lied and said he didn't spray anything (which was such an obvious lie, why lie???). More worryingly he recently burned a duvet at my parents house after staying the night and made a bullshit story about a cup getting too hot that it burned through the duvet. My mum found some weed in a drawer (so it's obvious that's what he was really up to) but is still adamant he wasn't smoking it and that his story that defies the laws of physics is what happened
. It's not the first time he has started fires which worries me and I have lectured him about how dangerous this is so many times. He stole money when he was about 10 (small amounts lying around) but would completely deny it even though he was the only one who could have taken it, stole from a gift shop when he was around the same age and I made him return it. When he was about 10 he lied about winning a regional maths competition at school and that he'd won an extravagant prize. He went in to lots of detail about it for over a week until I found out he lied.
He can also be extremely callous at times. He locked our dog in a cupboard recently and denied it, he will square up to his younger brothers and threaten them physically (and he is a big 15 year old) and used to tease and hit them relentlessly (and lie about it). More recently he went to DS13 who was innocently playing xbox and sprayed him in the face with fly spray and teases DS for having ASD. I've tried to talk to him about what might be going on so many times but he will not open up about anything. I've offered to pay for counselling but he doesn't want to do that either and I'm at a loss of how to help him.
He's doing well at school although he lies alot about migraines so attendance is slipping and he's often late. I know he's not happy but I don't know what to do to help him. I'm starting to worry this is more than "usual" teenage behaviour and he might have a personality disorder (his dad has one and I know genetics are a factor).