Some mentions of Charlemagne.

by SigbiasSilva , West Midlands, England, Monday, April 01, 2013, 08:51 (4253 days ago) @ CortanaV

Here are two mentions from Bungie regarding Charlemagne so far, though I may be missing some others. It should cut down your search for links ever so slightly.

I read the first at Polygon:

Staten recounted his own personal Destiny story, a shared journey with Jones as they traveled to the planet Mars. After meeting in the City's social district, they visited a hangar, where Jones' newly purchased starship awaited them. Together, they traveled to Mars to explore the ancient remains of a lost human civilization and recover an artifact in Charlemagne's chamber, a bounty commissioned by the Queen of the Reef.

And then one straight out of the Mail Sack:

The City wants us to recover a piece of Charlemagne, one of the great Warminds of the Golden Age—a vast machine intelligence built by the ancient Powers of Mars. The Cabal do everything they can to try and stop our descent, but we keep pushing, rifles cracking and Traveler energy boiling from our fists until the only thing left standing is us, and the only thing left of the Cabal is the loot they hid in Charlemagne’s vault.

That second info chunk is super exciting.

Hmmm. Perhaps Joyeuse is one of these pieces - a fragment of the Warmind AI Charlemagne - the fragment still individually a (somewhat?) functional AI in itself? Something along the lines of personality cores in Portal, I guess...