I read it a couple years ago so I don't remember everything, but I'm pretty sure it's not one of the ones by ariastor or omphalos.
Some of this might be wrong, but here's what I remember:
- it starts with the master being coming back via his ring somehow
- the master is working as a physics professor making some big machine at a university, i think in california
- the doctor & the master play some timelord game that involves tying yarn to a lot of objects and moving them around as if it was the time-space continuum, and in doing so, they realize that pulling gallifrey out of its time-lock thing wouldn't actually destroy the universe
- they fence in the tardis and im pretty sure it ended in sex
- the went to some planet and the master wandered off and the doctor freaked out because he couldn't sense him anymore (briefly)
- the doctor's daughter showed up at some point near the end of the fic. i can't remember if martha or jack were involved or not.
- im 95% sure neither rose nor torchwood were in the fic
- it was very long and written in episodes
- it had its own journal when i read it, it wasnt posted to someone's lj
- i read it in 2009 or 2010, but it was written earlier than that
does anybody know the fic i'm talking about? i can't find it for the life of me, but i remember it really fondly and i'm dying to read it again
i'd really appreciate it if anyone can help :)