Brand persona
A structured description of the brand itself: who it is for, what it stands for, how it sounds, and the impression it intends to leave. It records the brand's own identity and character in fields precise enough to write from, so that anyone or anything producing work on its behalf makes consistent choices.
Brand persona is not Buyer persona.
A brand persona describes the seller and a buyer persona describes the customer. One answers "who are we and how do we sound", the other answers "who are we selling to and what stops them buying"; using a buyer persona as a writing brief produces content aimed at a demographic instead of content that sounds like a company.
In practice
Every brand already has a persona, whether or not anybody has written it down. It lives in a founder's instincts about which words are acceptable, which colours feel wrong, and which kind of client is worth chasing. That works while one person makes every decision. It stops working the moment a second person, a freelancer, or a generative tool starts producing work in the brand's name, because instinct cannot be handed over. Writing the persona down is the act of converting a private sense of taste into something transferable.
The most common confusion is with a buyer persona, and it is worth being blunt about it. A buyer persona is a portrait of the customer: their role, their budget, the objection that stops them signing. A brand persona is a portrait of the seller: what the brand believes, who it refuses to be, and how it sounds when it writes. The two point in opposite directions, and a document that quietly mixes them produces copy that sounds like a demographic rather than a company.
The second misunderstanding is treating a persona as a character sketch. Giving the brand a fictional name, an age and a stock photograph is entertaining and almost entirely unusable, because none of it tells you what to write on a Tuesday. A persona earns its keep when it is specific enough to constrain a real decision. "Approachable but authoritative" constrains nothing. "We explain the mechanism before the recommendation, and we never use a superlative we cannot evidence" constrains a great deal.
Structure is what makes the difference between a persona you consult and one you file. Prose cannot be inspected, scored or partially updated; fields can. Separating audience, values, tone, proof points and the things the brand will not say means each part can be checked for whether it contains anything specific, and each can be revised without rewriting the document. Repic stores this as a structured brand persona for that reason: the fields are what let a quality score point at the single line that is too vague to write from.
In practice a persona is a maintained artefact, not a launch one. The offer changes, the audience narrows, a positioning line gets sharper in a sales call and never makes it back into the document. Each of those opens a small gap between the brand being described and the brand being run, and everything generated downstream inherits the gap. Reading the persona back once a quarter against the last month of published work is a cheap habit with an unreasonable return.