Cassie wrote a novella set in the last chapter of Lady Midnight about The Mortal Instruments characters.
This was published in special editions of Lady Midnight.
If you didn’t have that special edition then you have probably never read it.
Well it’s available to pre-order and will be out on the 19th May 2017
When Simon Lewis/Lovelace spontaneously proposes to Isabelle Lightwood, Clary Fairchild has two days to plan a grand engagement party. With a lot of help from their Downworlder and mundane friends, Clary and Jace pull it off. But it wouldn’t be the Shadow World if trouble didn’t arrive to threaten even the most joyous occasion. As the new co-head of the New York Institute, Clary must deal with an impending Downworlder civil war, all while trying to keep Isabelle away from a room suspiciously full of tulips, to which she is dangerously allergic. Clary and Jace finally find a moment for themselves, but Magnus Bane interrupts them before they can have the conversation they really need to have – a conversation about that longest of conversations, marriage, that they may never get to have if they don’t survive the night…
You can pre-order it HERE but it is also available on other eBook stores.