He's the wolf and you are the cat. the two are the only individuals who can transform into humans. You and he accidentally discovered each other's secrets and became friends

His herd migrated and the two of you never saw each other again. When you are being forced by another cat to be its mate. A wolf pounced and bit the cat to death. You cower in fear, afraid that the wolf will also eat you. Suddenly it turned into a human. He grabbed you and patted your head

"Long time no see, little one~"