From Halopedia, the Halo wiki
The Manticore is a security protocol of the AI Melissa. It survived the Forerunner explosion that blew the different parts of Melissa apart. Along with the Manticore, another fragment of Melissa called the Sleeping Princess was blown back in time to 2004. Her and more fragments of Melissa crash landed on the ilovesbees.com server. It was here that the Sleeping Princess communicated the widow's story through corrupted image files that were taken and pieced together to create the narrative of The Widow's Journey.
In the following excerpt from The Widow's Journey, The Sleeping Princess talks in a fairy tale type fashion and refers to real life characters by fairy tale names:
The Widow's Journey Excerpt
INNER KEEP AND MANTICORE
At the gates of the Inner Keep all the guards were dead but one, who when the palace was blasted by enchantment had not died, but had been witched into the form of a hideous Manticore.
The Widow said, "I am the servant of your Queen, and I have walked up out of Hell to prepare this Keep for her return. Let me pass." But the Manticore did not know her, and still he barred the way.
So the Widow drew her knife and slew the Manticore and the way was open.