I Masked Myself to Save Grandma

She goes to him under a name that is not hers, because her grandmother is dying and the treatment has to be paid for. What she gives him is part real and part worked out in advance, and she keeps testing where his limits are until he cannot do without her. His family is the other half of it. The house has a history it does not discuss, including relatives who lost their minds, and the courtesies between its members cover arrangements to have people removed. There is an old debt in blood between his family and another one, and the two of them are still at each other over property and control. Someone makes an attempt on his life. Her false identity does not hold. The truth comes out at a formal occasion, with blood on the ceremonial gown she is wearing.