Krogstad and Mrs. Linde come together under peculiar circumstances in A Doll's House. Importantly, Mrs. Linde holds a position of power in relation to Krogstad when she invites him to meet at the Helmer house in Act III. She now holds the job which once belonged to Krogstad and she knows everything about his treatment of Nora, his loan to her and the blackmail he has attempted.
Krogstad, on the other hand, is in a powerless position. Jobless and stripped of his honor and reputation, Krogstad has nothing to offer his children and no prospects for improving his situation.
Mrs. Linde, after losing her husband, wants to be needed again and to have someone to take care of. Krogstad and his children fit her desires and she makes an offer to Krogstad. In their conversation Mrs. Linde makes her motives clear.
Mrs. Linde's position of power over Krogstad and her clarity of purpose are both in contrast to Nora's relationship to Torvald.
Keeping secrets, breaking his rules, and feeling diminished by Torvald, Nora only speaks her mind when it is too late. There is no clarity in her relations with Torvald. Subterfuge and manipulation are her main tools when dealing with her husband - a stark difference from the way Mrs. Linde openly deals with Krogstad.
Nora resorts to manipulation because she has no real power in the her relationship with Torvald.
She is viewed as an object, a toy, a child, but never an equal.