Lackey, Mercedes, Eric Flint, and Dave Freer. The Heirs of Alexandria
Divergence: 415 CE
What if: Hypatia of Alexandria triumphed in her debate/conflict with Cyril and her philosophy was blended into Christianity.
Series note: Series originally announced as a tetralogy but which will include seven books if all are published. Includes The Shadow of the Lion, A Mankind Witch (by Freer only), This Rough Magic, Much Fall of Blood, Burdens of the Dead, All the Plagues of Hell (by Flint and Freer), and the projected The Great Doom's Image (by Lackey and Flint).

Lackey, Mercedes, Eric Flint, and Dave Freer. The Shadow of the Lion
Divergence: 415 CE
Summary: Murder, magic and intrigue in a 16th-century Venice, where the demon-possessed grand duke of Lithuania seeks to distract the attentions of the Holy Roman Empire.
Series note: First volume of The Heirs of Alexandria.
Published: Baen 2002 (0743435230BUY), 2003 (0743471474BUY).

Freer, Dave. A Mankind Witch
Divergence: 415 CE
Series note: Second volume of The Heirs of Alexandria.
Comments: Third published book in the series. It was not part of the originally planned tetralogy but was subsequently written as an intersticial work.
Published: Baen 2005 (0743499131BUY), 2007 (1416521151BUY).

Lackey, Mercedes, Eric Flint, and Dave Freer. This Rough Magic
Divergence: 415 CE
Summary: The Lithuanian attack against the Holy Roman Empire again focuses on subverting Venice, but this time through a Hungarian attempt to capture Corfu and thereby close the Adriatic.
Series note: Third volume of The Heirs of Alexandria.
Published: Baen 2003 (0743471490BUY), 2005 (0743499093BUY).

Lackey, Mercedes, Eric Flint, and Dave Freer. Much Fall of Blood
Divergence: 415 CE
Series note: A volume of The Heirs of Alexandria.
Published: Baen 2010 (1439133514BUY), 2011 (1439134162BUY).

Lackey, Mercedes, Eric Flint, and Dave Freer. Burdens of the Dead
Divergence: 415 CE
Series note: A volume of The Heirs of Alexandria.
Published: Baen 2013 (1451638744BUY), 2014 (1476736685BUY).

Flint, Eric, and Dave Freer. All the Plagues of Hell
Divergence: 415 CE
Series note: A volume of The Heirs of Alexandria.
Comments: Previously listed as Tooth of Wolf, Claw of Dragon.
Published: Baen 2018 (1481483617BUY).

Lackey, Mercedes, and Eric Flint. The Great Doom's Image
Divergence: 415 CE
Series note: A volume of The Heirs of Alexandria.
Published: Not yet published; no publication date announced.