My first (successful) venture into screenwriting was an adaptation of the Demonata series of books by Darren Shan. The adaptation is into a TV show, and writing the pilot episode was where I really discovered my love of screenwriting.
I only adapted the first 40ish pages of Lord Loss into a screenplay, adding and changing enough elements that without names or previous concepts, it could be mistaken for something else.
In realising this, I came up with a new story, which I adapted my adaptation into. This would be a story about witchcraft, spinning the idea of a witche’s familiar into a hideous creature that comes from hell not to serve, but to either be subjugate to you, or assimilate into you.
This story had a much more solid ending than my original adaptation, and I felt like it had a lot more interesting ways to be taken without it becoming too grand-scaled a story.
The first episode will be added to this site (once I work out how to add a PDF to it), and I intend to finish the first series at some point once I have all the plot points and beats laid out.