User blog comment:FairyRaven/Fairy Tail Chapter 465: 400 Years, Review and Commentary/@comment-24277053-20151207125720/@comment-71.222.52.171-20151208064349

This also fits with Grandine saying to Igneel that she had hoped that Wendy and Natsu would have a better relationship this time around (directly implying that 400 years ago as children they didn't have the most friendly relations) as well as Natsu remembering Wendy's name as if it were familiar just as she is introduces as a character (with all this it can be assumed that the dragons erased their memories on both of them but didn't work 100% on Natsu in order to give them both a better relationship this time and as well as making them forget about the time they did to get to the present time that they are in now)