Promises to Keep

Promises to Keep is one of several short stories in Halo: Fractures - Extraordinary Tales from the Halo Canon.

Official summary
"This story takes place at the close of recorded Forerunner history, during the events that followed the destruction of the Forerunner capital world by the rogue artificial intelligence Mendicant Bias (Halo: Cryptum) and the subsequent activation of the Halo Array to end the centuries-long war with the extragalactic parasite known as the Flood (Halo: Silentium)."