Clockwork Hummingbird

From THE EVERSTEAM CHRONICLES - BOOK ONE by Jude Matulich-Hall.

an excerpt

Clockwork hummingbird wings easily raced over the Acheron’s waters, making sure to shat upon poor Charon’s head, who swiped at it with his oar but missed. It zipped around the girding Minos’ head and dropped oil into his eye. It sped zigzagging around the three heads of Cerberus, making them quite dizzy as the monstrous jaws fought to snap at it. It flew over the Styx without a care. Had it been just a few kilometers to the left, it would have seen the small group, but alas, it did not. It taunted the furies that guarded the gates of the city of Dis for a while before zooming over the iron walls that surrounded it.
Rufus thoroughly enjoyed the form of a hummingbird while his brothers had taken the forms of the graceful heron, the powerful eagle, the gentle dove, and the diligent hawk. Why the hummingbird? It was unpretentious and agile, surprisingly aggressive. Aaand, he could hover, fly sideways, and backward!