Senator Empedocles is one of the restive, rebellious lawmakers of the Empire of the South. And the senators are revolting.
Their plot this time is to get rid of Claudia -- the halfblood child of the late Emperor and his marshwoman second wife, They take a legion that is loyal to the Senate, rather than to the young Emperor Titus, and take off for the Wizards University. A begging letter from Wizard Corkoran, which they waylaid, as they apparently waylay all of the emperor's mail, let them know that she was there.
Senator Empedocles and his fellow conspirator Senator Antoninus speak to Wizard Corkoran, suggesting in an oily fashion that, since they have concerns about the possible succession to the throne of a halfblood, and since they are the ones who vote to expend money in the Empire, and since the recent letter indicates that the University needs money, it would seem like a good idea to hand Claudia over to the Senate so that they can eliminate her, in return for a generous contribution to the university.
They say this in a very pompous and wordy way, which the Forgemasters (who have arrived at the same time looking for Ruskin) have to translate into plain talk.
Corkoran has realized that Claudia is valuable to him because she calculates so fast, and can be very helpful in his research, so he turns the Senators down, but alerts the Emperor in a pigeon message. If the Emperor is grateful enough, he figures, it will result in a donation anyway.
The two senators, when they are not busy putting down the humanity of the dwarves in snide whispers to one another, are forced to leave without getting what they wanted, but they issue a warning to Corkoran as they go.