Vampiric princess by K S (best ereader for manga txt) 📕

Silver is a 17 year old girl turning 18 in a few days, she lives in a foster home until a odd couple take her home. They say they took her so she would marry their son, but there's more to it. With everything clouding up in her mind she doesn't know what to do. What's worst is that their son has a girlfriend... that makes things a tad bit more complicated.