Slashy, smutty fun for everyone's favourite gay space pirate, Capt. Jack Harkness?
Torchwood, Whoinverse, cross fandoms and PBs. Thanks to the nature of the character it's pretty easy to explain away him turning up just about anywhere, anytime. Ha!
Though I would kind of LOVE an 11th Doctor for him to shamelessly seduce. ....yum.