Complex sentence: Jessie is demanding, not particularly studious, relying instead on her charm, and is the first person to call Peola "black" in a hurtful way, making it clear that their childhood idyll is doomed.
Split into simpler sentences: Jessie is demanding, not particularly studious, relying instead on her charm. She is the first person to call Peola "black" in a hurtful way, making it clear that their childhood idyll is doomed.