Heron Mill by K. L. Taylor-Lane

Mother says I’m strange.
After hiding me away in a school for twelve years, her new husband wants me home. To be a family.
Out in the middle of nowhere, the Blackwell family’s stone mansion stands tall. Heron Mill is hidden, tucked away deep in the forest, surrounded by nothing but trees. Something nefarious hides here. A sinister secret decaying in its basement.
And then there’s him.
My new stepbrother is unusual.
The things he does, different. His behaviour, curious. The way his dark eyes watch me from the shadows when he thinks I don’t notice, unnatural.
Wrong.
I can feel the darkness inside of him, cold and vicious. A sickness, something contagious, a poison seeping into my bones, disturbing something that long lay dormant. Something inside of me is starting to awaken and I’m really not sure it’s something good.