I have a grouchy old cat, love the bones of him. He is called Izzy - due to a slight gender mix up
any way, Izzy is extremely hostile. He won't let me pick him up, and I'm just waiting for the day my neighbour tells me he's eaten her little Yorkshire Terrier. I've tried everything with him over the years - he's just grumpy and does what he wants.
I got him when (IMO) he was far too young; only seven or so weeks. But in my defence, his mother had died and he was going to be drowned. 
He's now about ten years old. But I'm just wondering - because he was so young and didn't have a mother, (to keep him in line give him a little nip when he was naughty) did this contribute to his psychopathic highly strung nature? He's always been a biter. Literally would snuggle around you for two minutes and then sink his teeth in to your arm.
I know his signs and I can handle him. He doesn't bother with other people or children - but I've always wondered.
Please advise, lovely cat people 