Once he's sure Diarmuid is in place, Sam wraps one arm around the boy's waist -- tight enough to secure him, but not so tight that he's being squeezed. He places his other arm in front of them both, pressing against Dragonite's shoulders with his hand.

"Whenever you're ready, Dragonite! Just a couple of warm-up laps first." Dragonite croons in acknowledgement; now that all the riders that will be on its back are settled, it begins to flap its wings, and gently lifts off the ground. Before it goes anywhere, though, it scoops the Horsea up into its arms, positioning him so that he's both secure and has a good view of what's going on.

Once that's done, it begins to fly in earnest -- but still low and slow, barely above the ground or faster than walking speed. The riders could still jump off and not even get hurt, even. As Sam said, this is a warm-up, so that Diarmuid can get used to the feeling of flight, and the feeling of Dragonite's muscles working under him as its wings keep them aloft.