okay okay okay. So we all know that Erza taught Natsu to read and write. I personally like to think he could already just not whatever language was used in the present which is why he struggled. And that little scene is played off as a joke.
I think it goes deeper than that. We don't see anyone else offering to help him learn, in fact everyone makes fun of him for it. It's only Erza who steps up and offers to teach him, no matter how terrifying that process was.
The is, Erza never learned to read or write herself. Not well anyway. She grew up in a cult as a child slave. They would've had no incentive to teach their captives to read and write. If anything they would've had incentive to not teach them. If they can't read of write that means they become somewhat dependent on their captors.
So when Erza joined the guild and got a new eye she probably had to learn herself. And then comes along another little boy who never learned and she doesn't feel any need to make fun of him for his lack of knowledge. In fact I bet she felt a sense of kinship in him and offered to help him how others helped her.
Just Erza seeing a slightly feral Natsu and claiming him there and then is just heartwarming.








