Random observation time!
When Metatron first meets Ashley and Sarah, she's suspicious and unsure if they are good or evil, but will leave them alone if they behave. Fast forward to having spent time with Sarah (and Ashley, but probably more on the receiving end of pranks with Ash) and Metatron is gushing about how great they are, calling them both good girls and treating them as a proud mother would. Metatron is still suspicious of succubi as a whole but realizes she shouldn't just say "succubus = evil" because the two that she knows are wonderful to hang around. Love the character development! :)