To Own the Libs - The Bradford McKinley Chronicles, #4

How far would you go? Seven months ago, Lily started transitioning. It had been a quick, unexpected decision: meeting her classmate Anna and Anna's theyfriend Elanor at a party awoke something in her, and she came out the very next day. There were some hiccups along the way, to be sure. Getting from there to here has been neither simple nor easy, but with the help of her friends and her girlfriend, Lily managed to overcome all obstacles in her way: she's now a happy, fulfilled young woman, instead of the angry and depressed boy she used to be.
When she and her girlfriend are about to become intimate for the first time, however, Lily realises she can't stand it any longer. She has to come clean. She has a confession to make. She's been pretending to be trans the whole time. A young man from a conservative background decides to "own the libs" by transitioning, thereby proving anyone can do it, even if they're not trans.