|“||I am Syren. I am ageless. I come from the Islands. I am the Islands. When I call, you will come to me.||”|
–The Book of Syren
One of it's largest roles was that in the attempted invasion of the castle. When Septimus Heap was warned my Syrah Syara to seal the ice tunnel hatch, Septimus fails. Syren then allows Tertius Fume's army to pass through her cavern to The Castle. It was later trapped into a bottle, not unlike those that hold the warrior jinn that Milo Banda had found, by Jim Knee, Septimus's live jinnee.