Though never outright stated, Kid quite clearly suffers from Obsessive Compulsive Disorder. This condition at times handicaps him, and at other times makes him stronger. He is obsessed with symmetry, to the extent where it sometimes interrupts his fights. He believes symmetry to be an art, the supreme beauty, and he will take time off to admire anything that is perfectly symmetrical. When fighting against a symmetrical opponent, he is virtually powerless by his own choice, because he believes that he will deeply regret destroying something he finds so beautiful. On the other hand, when fighting against something vastly asymmetrical or somebody who has damaged the symmetry of something, Kid will go into a violent, blind rage, and fire with no mercy until that opponent has been completely annihilated. His many quirks, such as folding the toilet paper into a triangle, arranging the picture frame at the front of his house so it is exactly parallel to the floor, and ensuring that the length of the left and right candles are exactly the same, stem from the belief that a failure to do so would make him a worthless being that other people (and, oddly, sometimes objects) would shun. He finds asymmetrical objects disgusting, and thus, when somebody points out the fact that Kid himself is asymmetrical, he will go into a deep-seated depression -moping on the floor and calling himself a worthless pig. This, however, Liz and Patty can immediately remedy, by giving him encouraging words and trying to boost his self-esteem. On more extreme situations, where his symmetry is broken by an outside source (eg. getting his hair cut by Soul and Black*Star), Kid's body would somehow be adversely affected and he would cough out blood and pass out.

Because of his love of symmetry, he enjoys helping others become symmetrical as well -this evident in his attempt to persuade Liz to let him pluck her eyebrows. He is generally a helpful person, but his help is not always appreciated by others. This is because of his rampant nitpicking and the subsequently ridiculous length of time he takes trying to get simple tasks done perfectly right. At times, he assumes others will enjoy symmetry as much as he does -this evident in his arranging of the medicine cabinet so that it would be exactly symmetrical from Maka's point of view.

Not only does he enjoy symmetry, but Kid appreciates order and balance. The parties he plans are always formal and elaborate, and the speeches he gives are always meticulously long and proper. His goal as a meister and Shinigami is to create a neat, tidy and orderly world. However, he's not some kinda blind ideologist -he cannot deny that no soul is without evil. Thus, he believes that when a balance, an equilibrium, between good and evil is acquired, then there will be peace.