If there was one adjective you could use to describe Natsu Dragneel, it would have to be strong, Lucy decided. He had a crazy amount of raw magical power and special techniques that combined his dragon slayer abilities with a huge list of combat spells. He was undeniably strong to master such things - eating Laxus' lightning and making it his own? Absolutely amazing.
Come to think of it, though, Natsu was also caring. That was another good trait, right? Lucy was sure he cared about his nakama and even just acquaintances. After all, he'd stormed into the lair of Sabertooth at the Grand Magic Games and called out their master for the man's treatment of Yukino. That took guts and commitment and showed he was a special person.
Natsu was a promise keeper too, Lucy reflected to herself. She'd never known him to fail to do something he'd said he would. He tried his hardest and always came through for her and their guild mates. She'd lost track of the times he'd saved her life. Lucy chewed on the end of her pen, musing on a few occasions when she'd repaid the favour.
Smiling to herself, Lucy thought about just how hard Natsu fought for the things he believed in. He never quit, not on himself or on her. The more she thought about it, the more Lucy realized that Natsu was special. There was no one other person who embodied so many of the same positive qualities. Sure, Natsu had some quirks and foibles - he'd basically been raised in the wild and by a dragon no less! He didn't quite get the finer nuances of human inter-personal relationships - he was forever sneaking into her bed - but he always pulled through for nakama.
This is what Lucy was thinking of as she wrote another letter to her mother. She poured out her heart to the woman beyond the reach of mortal hands. Her missive detailed all the sterling characteristics of her partner, as she scrawled page after page of accolades for her best friend to the woman who would have treated him as a child of her heart.
Lucy found herself finally slowing down and considered how to end her letter. Biting her lip, she gripped her pen tight and listened to the steady beat of her heart. I love being his partner. You would have loved Natsu too, I know that I wrote earlier that he's got issues with human-interpersonal relationships...but as long as I have him, I don't need or want anyone else. Love, Lucy.