Natsu was known for silly expressions. He made quite a few of them every day, some on purpose and some in reaction to things that had happened to him.
His second favorite face to make was the Nina Face, first patented in the mansion of Duke Everlue when Lucy had said something about acting like ninjas. Because stealth reasons. And he knew Lucy found it funny, so that catapulted it up the list of favorite faces.
So whenever Lucy was feeling down, he would come in through her window with his scarf pulled up over over his mouth and nose, hands in ridiculous position, and talking in a smooth, clipped voice. All to make her smile.
And most of the time, it would work. Those times, he would come up with something else, or even just sit with her and listen to why she was upset.
Today, Natsu climbed in her window Ninja Style once again, but he could tell the moment he saw her face that none of his usual material would cut it this time. He sat down by her chair (still in Ninja Mode), where she sat with a sad look on her face.
"Why are you so sad?" he asked in the soft, clipped tone.
"Today's the day my mom passed away," she answered in an equally low voice.
Oooh... Natsu knew he was gonna step up his game. "Sorry, Luce," he said, still in the Ninja Voice. "Will Ninja cheer you up?"
She looked at him, just the hint of a smile on her face. "You're silly," she said softly, fondly.
He pulled down the scarf, giving her a consoling smile. "That's only my second favorite face."
The smile grew. "What your first favorite?"
"Your's," he answered, with just about the cheekiest (but still loving) smile in the world. Lucy blushed, and she could have sworn she felt steam rising from her skin. And she smiled a smile so bright the gloomy sky lit up.
Natsu almost gave a victory dance, but decided in favor of giving a wide grin instead. A victory dance was too much, even for him.