One day Natsu and his team went on a request. Seems pretty normal. The flier was written in simply terrible English.
Eventually, after some walking, they reached the house the client owned. Once they knocked on the door, They were met by a tall frail looking man who was obviously not from here. "Hello, hello, please come in," the man said in a heavy accent where his English was barely being recognized.
The team sat on the couch, expecting instructions on how to do their job. However, it was pretty obvious the man was having a very hard time. Natsu looked around in curiosity. The house exterior isn't from here and the floor is stained wood. Wait, what does that bit of text say?
While Natsu was trying to decode who this man actually is by his house, the client was desperately trying to speak, but couldn't. His English was barely coherent.
Wait a moment… that accent...
Suddenly, out of nowhere, Natsu spoke.
But not in a way anyone expected.
"Hallo. Ich bin Natsu. I can speak German, so no worries."
Natsu's team members' jaws hit the floor. The client, on the other hand, looked like as if God sent him an angel. "What he f—" Gray was interrupted by Erza's punch.
"Hallo. Ich bin Adel. Thank you very much. I thought this was a loss cause. I moved here from Germany not too long ago."
"It's okay. I became interested in German when I was young. So, what do you need?" Natsu comforted.
"Thank you, well, my children had disappeared a week ago and haven't been back since. Please, please bring them back to me."
"Don't worry. You're looking at Fairy Tail!"
Once Natsu translated all the details, Adel shook his hand in almost complete trust (who wouldn't if they found someone who spoke their language while being in a foreign environment?). The moment they stepped out of the client's house, Lucy screamed at him.
"SINCE WHEN DID YOU KNEW GERMAN?!"
Natsu turned around. "Igneel actually taught me German first before I learned English. Unfortunately, he wasn't too fluent. No one else knew German so I couldn't talk to anyone before."
Erza picked her jaw up the floor. "So you did know how basic language…"
"Yeah just not in English."
Team Natsu continued on with their search, with everyone behind Natsu in pure shock of this shocking discovery.
This is based on the fact Natsu's voice actor (Tetsuya Kakihara) growing up in Germany.