What do you think about the relationship between Nora and Krogstad?

Krogstad and Nora's relationship is tenuous. Krogstad is the man Nora borrowed money from to pay for trip to Italy. He is an acquaintance of Torvald's and an employee at the bank which Torvald has just taken over. Krogstad was involved in a work scandal many years previously; as a result, his name has been sullied and his career stunted. When his job at the bank is jeopardized by Torvald's refusal to work with a man he sees as hopelessly corrupt, Krogstad blackmails Nora to ensure that he does not lose his job.