Letters to the Lantern! (HP/DC): Of Brothers, Sisters, and a Green Kangaroo.
https://archiveofourown.org/works/539020.../140307025
tealruby Wrote:Green Lantern gets a letter from a middle child, eager to offload unwanted siblings and/or join her as a sidekick.
https://archiveofourown.org/works/539020.../140307025