Friederike
Isaac's step-sister
(she was adopted by Isaac's parents when she was a child) is a
sweet-hearted and gentle girl, altruist and self-sacrificing.
Knowing that there are no biological ties between them, she loves
Isaac in secret, even though she hopes that he will marry
Katharine. Moritz develops a possessive affection for her and
forces her to date with him; but these sentimental strains and
her pains at work undermine her frail health. She dies of
tuberculosis, surrounded by everybody's love.
