User blog comment:SageSlayer/Why does Erza treat Natsu differently than others?/@comment-28759676-20170301003325

Erza learned to admire Natsu for his reckless behavior yet bold and powerful actions, whether it be verbally or physically. Gray is powerful nonetheless, however Natsu possesses a unique personality of being fearless and putting his faith and beliefs in his friends. Erza thinks of Natsu probably as a younger brother of some sort, trying to look over him. However she knows too well that Natsu is capable of being independent and victorious through his strength.