Saga of the two Isabels, Leonardo & Raphael

Isabella d'este, a patron of the arts, met Leonardo da Vinci in 1500. She wanted to be painted in a flattering way, & would dictate the composition & colours. She had sued Bellini & wrote 53 letters to Perugino (probable mentor of Raphael) to finish an allegory she had designed. On her beseeching, Leonardo drew her profile in black & red chalk. However, in spite of many entreaties by her emissaries, he never painted her full portrait, as apparently, he had no wish to subject himself to her whims.

Even though it is claimed that she had Raphael also working for her, it is not clear what exactly it was. However Raphael did paint at least the face of the famous beauty Dona Isabel de Requesens in 1518, the rest of her portrait being painted by his assistant Giulio Romana.

Sources:

• Capra, Fritzof  "The Science of Leonardo"
  
• Hodge, Susie   "Raphael"