In a way, Aerith was reminded of summons from back home. Not exactly, since those were brief and she didn't think they could be considered partners exactly, but the more they battled the stronger the summons would become.

"I think I understand. So your emotions make them stronger? What about if you're in a lot of battles?" Aerith couldn't help asking questions - hearing about the differences between other worlds and Gaia just kept them coming.