Great choice. Prairie kings make fantastic pets. They remind me of cornsnake personality in a kingsnake body with kingsnake burrowing habits.

About your hatchling.. give it time. Hatchlings can be like that. I have some, and they are mean little suckers. My yearling is as calm as can be. Heck, even baby cornsnakes can be mean (for a cornsnake.) Baby snakes are often aggressive. It is instinctive behavior for a little hatchling. Many things could make a meal of a baby snake.
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Mark G
Whitewater rosy boas, mixed rosies
Prairie kingsnakes
Cornsnakes
Mtn kings (pyro, agalma)