Love.
For Natsu, love had always been something that he associated with Lucy.
Whether it started out platonically or has always been romantic, he never managed to notice. He loved her enthusiasm in joining Fairy Tail, he loved how easy it was for her to get along with his guildmates, he loved her bond with her spirits, he loved her courage in standing up for herself and the guild, he loved how she treated everyone she met with nothing but kindness and most importantly, he loved how she made him feel warm, loved and secured.
Perhaps for everyone else, security was something that only Lucy would get from Natsu and not the other way around. But truth be told, Natsu’s growing protectiveness over Lucy as time passes only happened because she was the one who made him feel safe and strong enough to do so in the first place.
“Natsu, are you feeling okay? Did Wendy treat you before you got on the train?” her brows scrunched in worry as she massaged his scalp.
“I saved some of those fiery chicken wings that you like so much while you were off busy punching Gray in the face.” She rolled her eyes at him though he could have sworn that there was a hint of a smile on those lips as she said it.
“I swear Natsu, if you come to me all beaten and bruised-up after your silly fights with Gajeel and Gray again after this, you’ll be having only Happy to nurse your wounds. Which I don’t even think he’ll care enough to do so in the first place.” She berated him as she gently rubbed salves on his bruised cheek. Natsu in turn, just grinned up at her in thanks because that was what she said the last time he got beaten up and yet here she was, treating his wounds.
“I won’t run, Natsu. It’s always more fun when we’re together, right?” She smiled up at him back then, putting her life on the line yet again, as long as she gets to stay by his side.
So yes, Natsu does in fact feel warm, loved and secured with Lucy. In turn, those feelings that she aroused in him were what drove him to continue to protect her and ensure that she always stays safe and by his side. Because of how she made him feel like he was important enough to be cared for, loved for, and fought for. How she always looked at him like he was the reason why she lived. It was scary, how she made him feel. Scary, because he never wanted to imagine waking up in a world and place where Lucy was not in it. Perhaps that was the reason why he continued to put an arm over her whenever he sensed a threat, why his eyes would always shift to her in a battle, why his lips would automatically utter her name at the first sign of danger, and why, without hesitation, he would always jump in front of her in the face of an approaching attack.
Because she made him feel protected enough in the beginning to protect her in the end.
Perhaps it was the type of love that started out small and continued to grow overtime, or it has always been there, and he never noticed.
All Natsu knows was that he had always loved Lucy from the beginning.
