This sounds like fun. We like fun!

An alien race consciousness-swaps one of their own into a newborn human to act as an advance observer, growing up as one of us, getting to know the biology, culture, language, etc. Said race has done this before--the consciousness-transfer is permanent, so they eventually extract their forward observers and use the insights gained to decide how to approach first contact. They are essentially the de facto ambassadors of a loose affiliation of starfaring races.

This time, however, things go horribly wrong in a way they are unprepared for. First, newborn humans are pretty helpless for a long while, which is inconvenient but well within mission parameters. Second, their forward observer is being abused and tormented by her own parents (although they are completely unaware that she's a, well, "changeling"). After something over a decade of this, she is finally able to escape her abusive parents and try to scrape together the materials to contact her people and get rescued. Her debrief will presumably lead to some ... very interesting discussions at the galactic UN about how to approach Earth (Rehabilitation? Quarantine? Extermination?)