The first clue, "Merry", opens the board with intentional ambiguity. In Pinpoint, a single clue rarely proves the category — it is a starting hypothesis, not a verdict.
"Sam" narrows the field. A valid category must explain both "Merry" and "Sam" with the same rule — not two separate stories.
By "Boromir", the category "Members of the Fellowship of the Ring (J.R.R. Tolkien)" should start to feel inevitable. Three clues with one rule beats three clues with three excuses.
"Frodo" adds another member of the same set. Each new row should strengthen "Members of the Fellowship of the Ring (J.R.R. Tolkien)", not send you hunting for a new theme.
"Gandalf the Grey" is the stress test. If "Members of the Fellowship of the Ring (J.R.R. Tolkien)" still fits naturally here, the puzzle is solved; if not, your category is too narrow or too broad.
Read together, "Merry", "Sam", "Boromir", "Frodo", and "Gandalf the Grey" converge on "Members of the Fellowship of the Ring (J.R.R. Tolkien)". That convergence — one precise category, five varied clues — is the structure Pinpoint rewards.