Final answer:
Henri is the guardian and mentor to Number Four, an alien disguised as a human to escape intergalactic hunters, in the novel 'I Am Number Four' by Pittacus Lore.
Step-by-step explanation:
The character Henri's job concerning Number Four, also known as John Smith, is as a guardian and mentor. Henri is responsible for protecting Number Four, who is an alien from the planet Lorien, hiding on Earth from intergalactic bounty hunters known as Mogadorians. In the story I Am Number Four by Pittacus Lore, Henri ensures Number Four's safety, assists in his development of Lorien Legacies or powers, and provides guidance and education about their planet's history and Number Four's destiny.