Ok:
Bartholomew will address the pit fiend with all of the dignity and flattery reserved for a high noble,
The upshot will be a highlight of what is actually going on (figure he knows most of it already and if not, some risks must be taken) and that we MUST get to the engine as soon as possible to prevent catastrophe to this place as well as the prime and other planes (I am trying to stick to the truth, so If what I just typed is not accurate - I'm absolutely meaning to be accurate). Basically explain our purpose and that we do not wish to otherwise impose.
I will also weave in, subtly, that while I am being polite, we COULD approach from a position of strength and force our way in - but out of respect (as I'm sure this being assumes he's due) are not doing so. Basically, convey strength as opposed to weakness,
The point will be to see if I can guide him to "decide" to show us what he can (hopefully a clear way to where we need to go).
That a pretty clear outline of what I'm trying to do?