He was just angry about his life, which I could understand. It must be horrible to be in the wrong body, to have this dual identity. I knew he suffered. I just wished he wouldn't take it out on me. (3.2)
Luna doesn't have an easy time with transitioning back and forth every day. In fact, she hates it. She hates hiding who she really is and is utterly spent from the effort of it all.
I hated when he got this way—depressive, suicidal. His pain was so palpable, it made me hurt. Huddling inside my parka […] I resigned myself to repeating my sophomore year. So what? How insignificant was school compared to saving my brother from himself? (3.49)
Hiding her true self has really taken its toll on Luna—and by extension, on Regan. When Luna gets depressed, Regan feels her pain as well. She can't help it because she loves her sibling so much.
I fall to my knees and clench his shoulders' start to shake him. "You have to throw up, Liam. I won't let you die!" This comes out a screech, which makes him raise his head and look at me. His eyes are already dead. (8.64)
There have definitely been close calls with Luna, who is so depressed by her life as a trans person that she sometimes feels like she can't go on.
It took a minute to 1) wake up fully because I didn't want my dream to end, and 2) calm Luna down. She was crying so hard, she was hyperventilating. (9.36)
Even the smallest thing can set Luna off, like their dad demanding that she try out for baseball. It's just another painful reminder that she's expected to live her life as a boy.
Tears stung my eyes. It wasn't fair. Why him? Why her? She was such a good person, Luna. Liam. The best brother ever. (14.100)
Life seriously isn't fair sometimes. Even though Luna is a great person and the nicest sibling ever, she has to suffer because people think she's different and a freak.
Anger roiled in my stomach. He was so wasted. So pathetic. I whirled. "You are pathetic," I spat at him. "God! I hate you." (19.25)
Ugh—yet another thing in Regan's life is ruined because she has a transgender sibling. Even though it's not really Luna's fault, Regan can't help but feel the painful loss of her babysitting gig and the disastrous effects of her date with Chris.
His sobs intensified. I felt myself weakening. It hurt my heart to hear him cry. But his tears were eternal; they'd never go away. (19.64)
Poor Luna always has to suffer alone. Even though Regan is always there for her, she can't always come to her aid—she's going to have to learn how to face the world by herself.
I wanted to go after Aly, but didn't know what to say to her. And I couldn't stand to see her cry. (23.80)
Luna's secret coming to light is hurting everyone—Regan, her parents, and even her best friend. But it's not Luna's fault. People just have to learn to accept her for who she is, even if they wanted someone different.
No, it would only cause him more pain when he found out the truth. And he didn't need any more hurt in his life. No more lies. (23.83)
All this lying has been destroying Luna's life and sense of self. Now that she's committed to transitioning, she's also committed to being honest in every way.
She should've told Dad. All these years he'd tortured Liam with the sports. His unrealistic expectations. He'd made Liam feel like a failure, feel inadequate as a son. (23.126)
Their mom may have known that Luna was trans the entire time, but she never did anything to stop her child's suffering, never stepped in to intercede or make things easier. Maybe she just didn't know how to help? Does that get her off the hook for watching her kid struggle alone for so long?