^ hmm taking a look at all the guys ..(and its exclusively males.. who did it ) since littleton its always been some sort of quiet outcast with no or few friends
many of them had no friends.. no girlfriend.. were socialy inept, have been mobbed at school.. had issues with their parents at home.. and nowhere to turn to . of course each of them had a different motivation and lifestory.and of course a different psychology. but there are always similar patterns
so they feel angry.. socially inferiour and rejected and if family school or anything else offer noone to talk to about their problems .. a few people ..like those did will resort to violence. and i would say most of them have had severe personality disorders.theydo it both as a way of revenge. feeling superior to others by taking their lives and "showing them" and for once getting some attention
it is both revenge for those that somehow wronged you ..and punishment for those that could have helped you but didnt
lets take a example of a patient with borderline disorder .shes a cutter and knows you care for her.. and if she feels is some way wronged because you let her wait before seeing her or were busy.. she would cut herself to the bone just to get at you.. and i think in some cases its something similar just a thousand times more extreme
