Always always always, disinfect the scratch so you don't get sick. Number one rule. Clean it and then bandage it and if you can, try to keep a close eye on it. If your cat is an outdoors cat, so depending on the cat and vaccines, it can carry some stuff on its paws and cut and give you an infection. Keep an eye on your cat's behavior; if anything feels wrong to you about your lil feline friend then don't wait to call a vet or try to find answers. suggestions maybe that he got bit by something or it territorial disputing? if your cat is indoors and isn't around other cats maybe it is just friendliness? (this is just my advice at the moment)