Wade of Aquitaine

Deep in the Dark Ages, with Vikings to the north and Aghlabid pirates to the south, a small flicker of the Roman Empire has been nurtured as an island of high civilization. Defeated Longobards scheme to bring it down from within. 

If Byzantium falls 600 years too soon, nothing of Western civilization will survive to spark the Renaissance. Enter Wade Linwood of the 21st century. Suffering of crossed senses where scents can conjure objects and sights can call up tastes, he wants nothing but the ordinary life of an insurance underwriter. 

When a trip to the acupuncturist opens an unused portal in his synesthete's brain, a plea from the past draws him to a time when he must save the remaining shreds of history to preserve his own.

"Many would be lucky to write a whole series marked by the wit and gift for swashbuckling action and romance that Parris builds into his debut.... A sharply intelligent and energetic historical fantasy." (Kirkus Reviews)