Science Fiction Black Red Green Purple Pink Neon Mystery Suspense Curiosity Book Cover Ideas with Shadows Girl Mist Boy Flames Red Hair Portal Green Eyes Test Tube Violet Eyes

The cover depicts the blonde-haired girl with violet eyes on the left side, her body angled slightly as she leans back-to-back with the red-haired boy positioned on the right. The boy holds a glowing test tube that generates a surreal gradient of red, purple, and green light, its fluid swirling as though alive. Behind the duo, a large, circular portal dominated by swirling, pink flames stretches across the background, its edges crackling with energy. Shadows and ethereal mist curl at their feet, enhancing the sense of mystery and suspense. The color palette features high contrast—deep blacks, neon highlights from the flames, and the glowing test tube juxtaposed against the characters’ more natural tones.

Sleek, sans-serif font in bold for the title "The Nexus Substance," with a futuristic, slightly warped design that mimics the portal's flowing energy. The text is placed above the portal, its letters glowing faintly with a subtle pink flame effect. The author name "Charlotte Janssen" appears at the bottom in a smaller, clean serif font, contrasting the title for readability and balance.

Centered composition with the characters and portal as the focal point. The title arches slightly over the portal at the top of the cover, with the author’s name aligned at the bottom edge. The glowing test tube is placed slightly off-center in the boy's hand, drawing the viewer’s eye. Shadows and mist coil around the characters, framing them and blending into the vignetted edges of the cover.