User blog comment:FairyRaven/Fairy Tail Chapter 456: Orders, Review and Commentary/@comment-1776824-20151010095429/@comment-7418318-20151010101559

But now the situation might have changed.

If Sayla also sees and hears through Mira's senses, she knows that currently FT is facing off against Zeref's troops. If she plays along with Mira (maybe even supports her) that would mean a chance (small as it is) to get close to Zeref and thus fulfill the purpose for which she was created.