[Suzerain of Sheol]

I honestly think just having them there all along would be by far the easiest mode of insertion. Short of some weird metaphysical reality-warping, no one got in here ahead of us -- the place was locked from the outside by the abbess and her flock fleeing as the infernal topos took hold over the local materium.

And it just strikes me as too coincidental that all these parties would converge on this remote site at the same time.

And furthermore, no one here is writing their magnum opus if there's a plothole in the beginning so we can get the story moving forward, so be it. I'm not really interested in what's gone before.