His Own Humanity is an AU series set in modern-day America (plus magic) featuring characters from Rurouni Kenshin (primarily Saitou and Sano) and Gundam Wing (primarily Heero, Duo, Trowa, and Quatre). Click here for ebooks, or, in chronological order (generally), the stories currently available are:
Seeing Red — Sano enlists the help of exorcist Hajime in discovering the nature of the unusual angry shade that’s haunting him
Plastic — Best friends Heero and Quatre have their work cut out for them assisting longtime curse victims Duo and Trowa
The New Familiar — During Plastic (part 80), Cairo thinks about thinking and other recent changes in his life
Fast Decisions — A look at how Hajime and Sano are doing
Get Used To That — A look at how Trowa and Quatre are doing
Reciprocity — A look at how Heero and Duo are doing
Cross-Cancellation — Couple analysis among Heero, Duo, Trowa, and Quatre
La Confrérie de la Lune Révéré — Quatre undergoes an unpleasant magical change; Heero, Duo, and Trowa are forced to face unpleasant truths; and Hajime and Sano may get involved
Guest Room Soap Opera — During La Confrérie de la Lune Révéré (parts 33-35), Sano’s 178-day wait is over as what Hajime has been fearing comes to pass
Consummate Timing — During Guest Room Soap Opera (part 3), Cathy learns a lot of interesting facts and Trowa is not happy
That Remarkable Optimism — A few days before the epilogue of La Confrérie de la Lune Révéré, Duo and Sano get together to watch football and discuss relationships and magical experiences; Heero listens in on multiple levels.