Bertram as Zeluco's foil: Bertram delights in helping others and values moral satisfaction over material comforts; Zeluco thinks only of his own pleasure and is disturbed by Bertram's mention of economy and charity.
Laura's near-death as the foil to Zeluco's: When Laura sinks into illness after her son's death, her servants dread her death; when Zeluco lies ill after the Portuguese's stabbing, his slaves mourn his recovery.