Same way an abused dog will flinch when you raise your hand. You recognise the signs of bad things to come. Most flinches are wrong, but if you're always quick

Same way an abused dog will flinch when you raise your hand. You recognise the signs of bad things to come. Most flinches are wrong, but if you're always quick on the defensive you don't get hurt as often. Someone looks shifty, or pauses at just the right moment in their sentence. Or scratches their nose while trying to get you to do something, or can't keep eye contact when they usually would. If they excessively look away for a moment during a disagreement get yourself ready to block the sucker punch. Or they accuse you out of the blue of doing something that's a complete 180 of your character -- ask them straight back if they're doing it themselves. I can't really explain it too well I realise, having edited this comment like 20 times, as I've only just started looking into it myself.