Both unilateral and bilateral contracts are enforceable in court. For example, a unilateral contract is enforceable when someone chooses to begin fulfilling the act demanded by the promisor. A bilateral contract is enforceable from the get-go; both parties are bound the promise.
Yes, scratching is a form of self harm. Try to tackle this problem while you can because it has the potential to get worse. I started out scratching and now I burn myself with a lighter and cut myself. It's a self-destructive way to deal with overwhelming mental/emotional pain.
Cuts, scratches, and abrasions can seem extremely frightening to children. Whether they skin their knees on the driveway, scratch themselves on a thorn bush, or accidentally cut themselves with a knife, children can go from being perfectly fine one moment to having a full-out screaming tantrum the next.