OMG! You took what could have been a prompt for some mindless PWP (not that there's anything wrong with that!) and turned it into something deep and powerful. I love how you wove original backstory with the mythical element of the twin heartbeats, and I got all choked up when I got to Jack's "new" favorite position, which really shows how he's evolved since meeting Ianto. <3<3
Re: Now here is the fill. I banished those pesky Cybermen...in the game at least.
Fantastic job. Thank you!