Why's Hayate surrounded by all of the dead people?
They all seem to be involved with the Tome of the Night Sky, i.e. the Book of Darkness.
The three on the left were resurrected in a vision shown to Fate Testarossa after being swallowed up by the Book of Darkness. Reinforce is obviously related as the prior master program of the Book of Darkness. Clyde Harlaown was killed in the previous Book of Darkness incident, although I don't know why he would be thankful to Hayate for that. I'm not sure how Granz Florian is directly related at all, except that the three souls released from the Tome of the Night sky in Nanoha Reflection played a pivotal role in restoring life to the Planet Eltria, which was Granz's life work.
They all seem to be involved with the Tome of the Night Sky, i.e. the Book of Darkness.
The three on the left were resurrected in a vision shown to Fate Testarossa after being swallowed up by the Book of Darkness. Reinforce is obviously related as the prior master program of the Book of Darkness. Clyde Harlaown was killed in the previous Book of Darkness incident, although I don't know why he would be thankful to Hayate for that. I'm not sure how Granz Florian is directly related at all, except that the three souls released from the Tome of the Night sky in Nanoha Reflection played a pivotal role in restoring life to the Planet Eltria, which was Granz's life work.
Granz first appearance in the franchise was the video game, Mahou Shoujo Lyrical Nanoha A's: The Gears of Destiny. A sequel to The Battle of Aces game. The Reflections/Detonations movies happen to use the two games as a source in the broadest sense of the term.