Who is Erasmus Kemp from Sacred Hunger and what is their importance?

Erasmus Kemp is the antagonist in the story and the first character introduced. His emotions are swayed quite easily by his circumstances. He is both annoyed by and proud of his father and suffers from other mood swings due to his love for Sarah Wolpert and his hatred of his cousin, Matthew Paris. His love for Sarah is physically and emotionally painful for him. He wants to propose marriage but is stopped by Sarah's father until Sarah is eighteen, which seems to bring Sarah relief. As time grows near to Sarah's eighteenth birthday, Erasmus finds his father hanging in his office; he has committed suicide. This changes Erasmus' life forever. His engagement and relationship with Sarah is ended, and he spends the next twelve years building up wealth and restoring his father's good name.