Didact

The Didact was a Forerunner Promethean, who held an extremely high status in the Forerunner society as supreme commander of the entire Forerunner military. He wholeheartedly believed in the "Mantle of Responsibility" the Forerunners held to protect life, and initially opposed the Halo Array as a sin beyond measure. He was also the lover and husband of the Librarian, and the one who eventually activated the Halo Array. Although he was abandoned in a Flood-infested system by the former Master Builder Faber, he lived on by implanting his consciousness within a young Builder known as Bornstellar Makes Eternal Lasting. He believed the Mantle of Responsibility should belong to the Forerunners alone and saw humanity as a threat rather than the successors that most other Forerunners saw them as.

adj.
1. Intended to instruct or inform or inclined to moralize excessively. (e.g., a didactic story)

2. A word that is overused by English majors as a pretense to sound intellectual when they are actually stating an obvious and trivial fact.

a speech or writing that is didactic is intended to teach people a lesson