The fiduciary is an agent of the estate with a duty to act in the best interest of the beneficiaries of the estate. The first thing to understand is that a fiduciary relationship is a particular type of relationship discussed in the law. It involves a principal and an agent. In the estate context, the agent is the fiduciary. They must act in good faith and in the best interests of the principal/beneficiaries.
In an estate, the principals are heirs, legatees, and beneficiaries. So, in an estate, the fiduciary can take on a couple of roles, which can be confusing. Is there a will or no will? If there is a will present in an estate, there will likely be an executor or executrix named as the fiduciary. An administrator or administratrix will be named as fiduciary if no will is present.
The three primary roles that come to mind are the collection and preservation of assets, payments of debts, and distributions to heirs, beneficiaries, and legatees. A court appoints the fiduciary, and then a timeline runs as part of a full administration probate estate.