24 parts Complete Angels weren't supposed to be birthed through the human race. It was a complete mistake that Zamora, or Emma as they call her on Earth, was there. It was necessary that she be brought back to heaven, for Zamora was meant to be a righteous ruler alongside the secondary queen angel, a huge step down from God himself.
The girl, now a teenager, would be brought and married to Michael. He was a noble prince, an ideal suitor for her. That very angel would be the one to bring Emma back to heaven but he had to do so before her age strikes twenty.
The only way for Zamora to come back would to be through an angel or demon, but there were none present on Earth. Michael homeland where she belongs. It's only when Lucifer's servant is sent to bring the princess to hell, falls obsessively for her when the true problem occurs.