Towards the end of the book, there is a scene which involves an ominous blossoming of a flower atop a podium in a lecture hall. I would like that flower on the cover. The an exert from this scene describing the flower is provided here:
"[The engineer] stepped back as the vine looped around the top of the podium, then stopped abruptly half a meter up into the air. He watched, transfixed, as the upward pointing tip of the vine swelled, then produced a bud. The bud bloomed into a menacing looking flower with long narrow black pedals dripping out from a central arrangement of smaller pedals the color of clotted blood."
That said, I am open to other ideas.
I have received a lot of questions about the flower and vine. So, I will do my best to describe this. In my mind, the flower itself looks something like a ghost orchid, except that it has more of those "dripping" pedals and is black instead of white. The vine is very simple (like the stem of an orchid), but might have curling out-shoots or a few scattered branches.
The book is titled "The Prisoner" because this is what the vocunine (the wolf-like creatures) call the naverkoo. The naverkoo is an ancient entity living deep inside the mountain. It is difficult to give a brief description of the naverkoo, but I will try here. Imagine a tree with "branches" that can be like vines or like regular branches, or like the tentacles of a jellyfish, or like blood vessels, or roots, or whatever else you might imagine. This "tree" has a central mass which is almost entirely made of what you might call "stem cells" - they can become cells of any type and can multiple indefinitely without diminishment. This is where the story gets pretty Sci Fi (biological science fiction). The naverkoo made the mountains by gradually pulling stone and soil up around itself using its vines/branches/tentacles.
This flower I am referring to grows out of a vine which the naverkoo has grown into the meeting hall at the very center of Pegasia - it is an ominous showing of presence and power. It is saying, without words, to the Pegaseans "there is no place in your City I can't reach and no one among you I can't touch."
Here is the passage from the book where Maria meets the naverkoo:
"What Maria saw when she reached the heart of the mountain took her breath away. This was no tree. The main body of the naverkoo was vaguely shaped like the trunk of a massive tree, but that was where any meaningful comparison ended. From inside the bottom of the cave, Maria could see the massive “branches” of the naverkoo extending into every direction, up through the massive stones and crystal boulders of the mountain, and down into the floor beneath her. Thousands of vine-like tendrils hung down lazily from the ceiling and swayed slowly as if caught in a breeze from another dimension. Some of the tendrils looked more like jelly-fish tentacles than vines, while others looked more like Spanish moss and still others looked like nothing organic she had ever seen before. Just as Maria reached out to touch one of them, the cave began to glow softly with bioluminescent blue light."
Also towards the end of the book, the naverkoo entrusts Maria with its "baby" (seed, larvae, whatever you want to call it). At first, Maria only looked at it. It was about the size of a golf ball, dark green and round.
Here is the passage describing the "baby" naverkoo:
"To Maria, it looked like a sea urchin with wilted spines or like a large burdock pod. Tentatively, she brushed the urchin’s “spines” with the tips of her fingers. As she did so, the wilted spines turned into tentacles which wrapped and curled around Maria’s fingers. The creature pulled itself up onto Maria’s hand, then nestled into her palm like a heat seeking reptile.
Maria lifted her hand up to her face and looked at it more closely. Scattered among the tentacles, she saw little nob like structures that changed colors in the swaying light above them. The naverkoo told her that these were its eyes."