My Grandfathers a Villain in a Romance Fantasy Novel (BL)

Willow, in his past life, briefly heard of a romantic fantasy novel - Flowers of the Sky Palace. In it, there was a horrendous dangerous delirious villain who plotted the fall of a kingdom and assassination of the royal family. The only problem was - he couldn’t correlate his now grandfather who raised him with warmth and love with the evil man described in the book. Determined to get revenge for his grandfather and clear his name, his decides to do what his family is known best for. Regicide.