If you are scared of a kid, what does it tell about the parents?

I would be friends with the Pongs (using a similar name).  They are a nice couple - he is a technician at a local hospital and she runs all kind of strange (I suspect not exactly totally legit) businesses.  When I ask her what she is doing, she would look through me and start talking about TV shows or mutual friends.  I am quite curious actually, but I guess it is better not to know some things about your neighbors.

So occasionally they invite me to join them for a tea and a round of poker.
She makes really good tea, but serves some fake home-made desert.
I know it is fake because: a) it tastes exactly like that pound cake from Lucky; b) I was helping to clean dishes once and actually found one of those clear boxes in her garbage can.
But it is ok - the way she reheats it and pulls out of the oven is kind of adorable.  I don't think her husband knows she fakes cooking.

But they also have a kid.  His name starts with S and it becomes him.  He reminds me of some scary character from a horror movie who keeps saying "SssssSSSsss...".  Ok, I am making it up - I don't know such a character, but if it existed I know how it would look like..

He is always sitting on a sofa, holding some game device and playing it almost without looking.  He is 10, but looks much younger, very thin, pale.
I don't know why he hates me, really.   Maybe because when I saw him for the first time I tried talking to him.  And I guess I interrupted some important shooting session.  But he always stares at me when I am around - without blinking, heavy, angry look.  Almost as if he wished he could do to me what he does to those inside his game.
And how can you tell parents that you don't want to come over because you think their kid wants to kill you.  (not him on a pic, of course - just somewhat similar)