- "My dhampir mother was Scottish - red haired, with a ridiculous accent - and I'd been told my Moroi dad was Turkish. That genetic combination had given me and my sister the same colour as the inside of an almond, along with what we liked to think were semi-exotic desert-princess features; big dark eyes and hair so deep brown that it usually looked black."
- —Isabelle on her physical appearance
Belle is described to be extremely beautiful and exotic looking, like her sister. She has large, dark brown eyes and long hair so deep brown that it usually looks black. Her hair has an tint of red. She stands 5'7" tall, with an curvy and athletic figure which is common to most dhampirs. Her exotic physical appearance is the result of being product of a mother Scottish descent and father Turkish descent. People gets confused which is which of Rose and Belle, being twins.
- "I am the calmer twin"
- —Isabelle on her difference from her sister
Belle is loving, caring, protective, sarcastic, fiesty, strong-willed, proud, stubborn and impulsive like her sister, but lesser. Belle is less snappy and reckless unlike her sister, she is more calm, and thinks before acting. She can be stressful and angry of the effects of the Spirit's darkness. Belle has an good heart and only wants to protects those she cares and loves about. She is an very committed guardian, and will face death to protect Rose and Lissa.