Older sibling
A brother or sister born before you — the first peer you knew, the one who arrived in the family before you did.
An older sibling in a dream is the dream's image of the first peer you knew — the one who arrived in the family ahead of you and set out some of its early terms. The older sibling is part rival, part guide, depending on the year. The dream brings the older sibling when something in your life — a competitive friend, a partial mentor, a figure who keeps appearing in the senior position you wish were yours — is being read through the very old template of how that first relationship went. An older sibling respected and learned from is the dream affirming the honest use of the early model. An older sibling resented for occupying the older position is the dream noting that the original arrangement is still playing out, and the resentment is older than the current scene.