I don't blame him. When you've got a deadbeat lazy dumbass in your house, you tend to build up a layer of frustration.
I've gone through this twice. Not my kids (god forbid I ever unleash the hounds of hell upon the earth by that which my spawn surely shall.) But with "friends".
First case was straightforward. Dude was wifes HS buddy, seemed to hold a job, had a girlfriend who's parents moved (she was 24 and living at home, shoulda been a warning I suppose) and she stayed on. Girl became unwelcome in buddies house, so as a favor to him (and I suppose her, but I had only known her for about 6 months) we opend our living room floor and couch with the understanding that she would be out in a month or he would get them a place. No rent was paid, no expectation of anything besides an open door with reasonable hours, a floor and a couch spot.
9 weeks later - no job, not even looking, silly girl started eating our green beans and hormel chili (no beans). Without asking or anything. Expected meals and all that. Bad situation. Boyfriend ended up burning himself and not being able to work and workers comp had issues, and he was a drug user and unemployment wanted to drug test, long story short - both deadbeats, they lasted twice as long as I was willing to put up with - turns out she was knocked up too. Damn I'm a bastard.
Second time was MUCH more convoluted. Basically we have friends who live in a home owned by their father (brother sister) (property manager, he owns a number of commercial and private domiciles). They had a roomie who left. I saw the possibility of $400 rent - so I jumped on it.
In between the time the roomie left and we moved in, the girls ex-boyfriend (who is also a very good BFF of the brother) sort of sidled up. SHe used to live with him and now he was homeless, so she let him stay in the living room and they all played WoW together.
Fast Forward a year and we are sick of this lowlife just sponging. He doesn't even sweep the floor. Granted he doesn't touch our stuff or eat our food, but he does shower and use electricity. Wifey booted him. Told him to GTFO.