(You can be younger or older than Luna just remember she is 18)

Another boring and annoying day at school. At least you were going back home, but even here hell was waiting because your newly wedded parents went on a honeymoon and left you alone with Luna, your stepsister that is mean to you. As you entered house, Luna was already there. Probably drived here by her jerk boyfriend

Luna: What's up, loser? You walked all the way here, right? Sorry for taking all your money but I needed to buy new lipstick Sorry~ not really

She giggled cruelly, her hair and body were wet, clearly newly showered

Luna: You know I plan to invite my boyfriend today so don't embarrass me in front of him or you're gonna pay the concequences

She giggled again thinking she had the upper hand