Settled in the story
Why did Harry's first Snitch matter in the end?
Snitches are never handled with bare skin before a match, because they remember the first flesh that catches them. The trail runs from a mouth-catch in book one to a will-reading in book seven, and ends on a walk into the forest.
This thread gives away a resolved story point
The clue
A golden ball caught almost by swallowing it, in a schoolboy's first match — and an enchantment that remembers exactly whose skin first touched it.
The trail
- Book 1 · Quidditch
In his first match, Harry spots the Snitch, dives, claps a hand over his mouth in mid-air — and lands with the ball in it, having nearly swallowed the thing in front of the entire school. It is played as slapstick: the boy who caught the Snitch with his face. File it away.
- Book 7 · The Will of Albus Dumbledore
The Minister himself explains the rule. A Snitch carries a flesh memory, and the one Dumbledore left Harry is the very ball from that first match: it will not open for Scrimgeour or for any stranger's hand. Pressed to Harry's mouth — where it first met him — it shows writing, a few words about opening at the close, and stays shut.
- Book 7 · The Forest Again
Walking to die, Harry puts the Snitch to his lips and tells it, in effect, that he is ready. It opens. Inside is the Resurrection Stone, carried for six years inside the first thing he ever caught.
The payoff
Dumbledore hid the Resurrection Stone inside the first Snitch Harry caught, sealed by an enchantment keyed to the catch itself, so that only Harry could reach it — and only at the close. The joke catch in book one was the lock being fitted.