Dark fall's secret maiden

As the moon was full and sky dark, after y/n ate dinner. Nergal decided to give y/n fresh air as he pushes her wheelchair around the castle and out, reaching to the garden.
"isn't the moon today beautiful?"
"yeah"
they both looked up to the sky and having a moment of silence, which was comfortable for the both of them, until y/n broke the silence and asked in a worried tone.
"how is leon doing?"
Nergal looks at her before leaving out a chuckle.
"your worried about him even your in that state?''
''answer my question before I get really pissed"
Nergal again chuckles at her annoyance and proceeds to push the wheelchair and began to walk around the garden.
''If I told you, you would get mad. Am I right?
She sighed heavily before speaking in a calm tone.
" I won't get mad, promise"
" Leon is now resting because of me"
Y/n looks back and finds nergal smiling. She slaps her forehead and sighed in annoyance.
" you guys can't even have a single day of not railing him"
"do not worry, I took care of him"
She nods in understanding and leans back on her wheelchair. The silence came back as they continue to walk around. But of course, silence never stayed silent for too long as nergal asked y/n a question.
"So? aren't you gonna tell me the reason you've hidden your identity."
Y/n flinches at the question before gathering the courage to speak.
"I've been use to it and thought it will be good for me to play it safe while fighting"
"Is it because of your tribe?"
As she heard this, she gets startled and leans down as she grips the armrest of the wheelchair before calming down and speaking coldly. 
"Our tribe had strict rules, and one of them is forbidding a girl be an only child''
Nergal was surprised at her sudden change of tone and expression, he can tell that she hated talking about her tribe.
"why is that?''
"its because they don't believe that a female can't provide the family and should instead take care of the house and children. But looks like luck wasn't on our side as my mother died when she gave birth to me."
Y/n looks up to the stars and took a deep breath before proceeding.
(name) tribe
Where we have our own roles to play. men do all the work while woman stay at home and be the light at the home. Children get education but separately.
Boys were taught swordsmanship, hand to hand combat, crafting and many more that will be used and helpful to the community.
Girls were taught sewing, cooking, planting and many more that will be used and helpful to aid the community.
Magic was also assigned. Boys were taught attack and protect magic. While girls were taught healing and simple attack and protect.
All is great but there was a problem, the family should a girl and a boy, each in the family. But unfortunately my mother passed away after giving birth to me. I became an only child until father married another woman but again, luck wasn't on our side. I became a big sister and I was happy that time. Not until my father forced me to change gender to male because if I don't. Its either i get killed or my sister. 
So I did what's best ............
.............just to protect my sister.
" so that's why, its for your sister"
"yeah, I didn't want her to die just because of that dumbass rule"
"why create such rule though?"
"don't know either, but all I can say is that the rule itself is pretty old"
She says in an annoyed tone which made nergal earn a small laugh.
"what's so funny?"
"nothing, its just, your story is different from the books but had small similarities"
"oh that, so you knew. Why even bother asking then?''
"I just want to hear it from you than believe in an old book that existed thousand years"
Y/n just smiled awkwardly at him before seeing that they arrived at her room. As they went in, nergal carried her to bed and gently puts her down.
 "Rest up dear, there will be an upcoming battle ahead of us."
Bonus:
minion 1: why are there many wheelchairs and healing medicines?
minion 2: apparently, after finding out master y/n was a woman. Many of her followers gave her this.
minion 1: master y/n's a female?!
minion leader: what are you guys stalling there? get back to work!