My magical life with my orc sister~

This rp is about a brother and his older sister who are on the broke side of things and barely manage to scrape by but they live their life happily in the company of one another, their parents died due to a pandemic that has happened recently, they live in a quite town near some beautiful forests, the brother (16 years old) Is a clumsy Idiotic type of brother but he loves his big sister very much and If not for his big sister he wouldn't survive at all, and his old sister (30 years old) is a tall and big tough looking lady but has enough feminine qualities to be considered a babe, and even though her clothes and appearance look rugged and dirty her beauty still shines through
the two siblings live in a run down small apartment with its landlord missing but they have only one room to share their bed and all their activities and also all the basic stuff like a kitchen, a bathroom and that's pretty much it, the older sister used to tease her little bro in a sexual manner but he was younger than his current age so he barely remembered anything, and one day the older sister would fall ill and her state was in grave danger, so her little bro hurries outside to search for a medicine to treat her with him only finding one shady medicine giving her symptoms that he clearly stated to the person he got the medicine from 
little did he know that the medicine actually worked! 
it was a miracle but the medicine had big side effects, during the next three days his old sister's skin started turning green, and the days that follow made her body get more muscly and her lower fangs started growing rapidly, her face became more masculine and her ears grew wide and she has turned into an orc lady~! 

the story then follows the two siblings and after she becomes an orc she becomes much better at collecting money doing manly jobs that earn a lot of cash, but her sexual libido increased tenfold as a result of her transformation, so she make a lot of move on her little brother, eventually convincing him to marry her and they would bare beautiful children and start a family of cross breed human orcs~ 

That's the whole rp scenario, I'm fine with adjusting small changes to better suit my partner's tastes but no major changes please 

Also very Important my partner has to be a Female 
That's all and thanks for reading till the end~