Is she a blessing or a curse

Melody smith is an assassin and doctor in the 21st century. She transmigrates into a book her friend made her read. She’s supposed to keep all the main characters alive. She thought it was simple enough. “After all, I only need to stay away from the main characters and avoid setting off the plot!” Little did she know… “Hey don’t you have someone else to bother your Highness!” “You’re the female lead, you can’t be this shameless!” “You’re my brother!” “Only by adoption!” Join Melody on her exhausting journey to save all the main characters.