I love the 19th century sentimental style you've had Narcissa write her diary. This scene was intense, very well executed, too, which I find hard to do when "diary text" is cut with a character's thoughts, like here with Lucius's thoughts. The emotions come full circle in the end, with the possibility of Narcissa appearing in her portrait suddenly opening up. I loved that!
I admire the way you characterise Draco here, his deluded obsession with revenge and his scheming seduction. The UST is intense here, both because you have us readers hoping that Draco eventually can give his feelings free reign, all the while hoping that Harry will not be badly hurt in the end. Thanks for writing this story!