Been staring at Wizeman for a while, here be some of my current headcanons, some of which I adopted from some other folks
Though he wishes people to see the darkness and the beauty within it, he has trouble getting this to happen.
Perpetually intimidating. Capable of spooking someone just by telling them to eat their veggies.
Difficult to communicate with him if you don't already know how he communicates.
If you somehow (EMPHASIS ON SOMEHOW) get him to give you advice, it will be a bitter pill to swallow, and he's not going to dampen that effect. But you will benifit from said advice.
Can grant wishes. Utilizes Monkey's Paw rules unless an idiya is surrendered.
Has survived terrible chaos in his early years of existence, which led to him creating Nightmare. Definitely a utopia compared to what was before.