Valentin told Nina about his childhood being a hunchback when he was friends with Anna. It was pretty sad. She was actually one of his only friends. However I think he liked her as more than just a friend and she rejected him in that way. Though I might be reading too much into what he said so if anyone else heard the conversation, I would love to hear your take on it.
He ended up having several surgeries which corrected his back. I'm thinking he might have had Cerebral Palsy if I'm remembering correctly. It was pretty sad and heartbreaking the way he described everything and you could see the anguish in his face. I thought he did some pretty good acting.
Nina was very understanding and compassionate with him when he shared the story which just made her more likable in my eyes. I still see her as a 19 year old just learning about life after all those years in a coma.