The Everything-but-the-Kitchen-Sink Series.
The following stories comprise an interlocking series involving characters from both shows and taking place in an alternate timeline.  In all, the series includes the following pairings:  Xena/Gabrielle, Hercules/Iolaus, Xena/Hercules, Xena/Callisto, Xena/Lao Ma, Iolaus/Ares, and even a smidgen of Callisto/Gabrielle.  The stories are listed below in chronological order.

Forced Revelations--by Ruth Gifford and atara
Pairings:  Ares/Iolaus, Hercules/Iolaus.  Rated NC-17.  Summary:  A brutal assault forces Hercules and Iolaus to face their feelings for each other.  (In 2 parts) (Text-only version here)

Never Let Me Down Again--by atara
Pairing:  Hercules/Iolaus.  Rated NC-17.  Summary: Iolaus reflects on the aftermath of Hercules' marriage to Serena.  (Text-only version here)

. . . But We're Not the Same--by atara
Pairing:  Xena/Gabrielle.  Rated PG-13.  Summary: After the events of "The Debt," Xena and Gabrielle discuss some of their differences. (Text-only version here)

How Long Till My Soul Gets It Right?--by atara
Pairings:  Xena/Gabrielle, Xena/Lao Ma.  Rated R.  Summary:  While Gabrielle sleeps, Xena has a conversation with the spirit of Lao Ma.  (Text-only version here)

This Must Be the Place--by atara
Pairing: Xena/Gabrielle.  Rated NC-17.  Summary:  Ares tests Xena to try to demonstrate that her relationship with Gabrielle is making her soft.  (In 2 parts) (Text-only version here)

The Dark Side of my Soul--by atara
Pairings: Xena/Callisto, Xena/Gabrielle, and a hint of Hercules/Iolaus and Xena/Hercules.  Rated NC-17.  Summary:  Callisto takes Xena captive and forces her to undergo a harrowing process of self-discovery.  (In 4 chapters)  (Text-only version here)

Idylls of the Conqueror--by atara
Pairings:  Xena/Hercules, Xena/Gabrielle, Hercules/Iolaus, Ares/Iolaus, Callisto/Gabrielle.  Rated NC-17.  Summary:  In an alternate timeline, Ares takes revenge on Hercules.  (In 9 chapters and an epilog)  (Text-only version here)

Blood Sisters--by atara
Pairing:  Xena/Callisto.  Rated R.  Summary:  Callisto consoles Xena on Gabrielle's wedding night.  (Text-only version here)

Twisting in the Wind--by atara
Pairings:  Hercules/Iolaus, Iolaus/Nebula.  Rated NC-17.  Summary:  Hercules and Iolaus do some "processing" after Hercules' return from Olympus in "Reunions."  (In 2 parts)  (Text-only version here)

  War God Lust--by atara
Pairings: Xena/Gabrielle, Xena/Ares.  Rated NC-17.  Summary: Gabrielle asks Xena to relate her fantasies about the God of War and is inspired . . . (Text-only version here)

In Hell--by atara
Pairing: Xena/Callisto.  Rated NC-17.  Summary: In Hell, Callisto finds herself in the hands of the Xena From Hell.  (Text-only version here)

A Taste of the Warlord--by Charmer
Pairing:  Xena/Gabrielle.  Rated NC-17.  Summary: Women, sex, bondage, a whip and a black fur rug.  (Text-only version here)

The Price--by Valentin
Pairings:  Hercules/Iolaus, Ares/Iolaus.  Rated NC-17.  Summary:  Iolaus pays a high price to Ares to save Hercules' life.  (Text-only version here)

Lightning--by Valentin
Pairing: Sovereign/Iolaus.  Rated NC-17. Summary:  Iolaus has an encounter with the Sovereign that leads to some unexpected results.  (Text-only version here)

Lightning II:  Beloved Stranger--by Valentin
Pairings:  Ares/Iolaus, Hercules/Iolaus.  Rated NC-17.  Summary: In an alternate reality, the son of Zeus and the lover of the God of War meet for the first time.  (In 4 parts)  (Text-only version here)

Dangerous--by Valentin and Rudy
Pairing:  Hercules/Iolaus.  Rated NC-17.  Summary:  Hercules conquers and learns the meaning of surrender.  (Text-only version here)

Disclaimer:  The principal characters in the stories listed on this page are the property of MCA/Universal and Renaissance Pictures.  No copyright infringement is intended, and no financial profit is anticipated.