Fiduciary relationship: duty to act for another's benefit with candour, confidentiality, and avoidance of exploiting trust. A fiduciary relationship exists when one person must act for the benefit of another, owing duties of candour, fidelity and confidentiality; it arises where trust and special confidence create superiority or control, or where one undertakes to advise or act in matters within the relationship's scope, and requires the fiduciary to act primarily for the beneficiary's benefit and not disclose entrusted information to third parties.