If Pasteur accepts, I repeat my first post of this thread, modified as follows.
"Most Noble Pasteur, I am fascinated by this your world. I would greatly like to learn more of it, your technology, history, faiths, and philosophies. It seems that the Silver Cabal, and yourself, have done much good for Earth. I beseech your aid in the name of liberty, fraternity, and equality."
"From what I understand, Edward Jenner, if I have the name right," Ardan says, trying to pronounce the name of this English predecessor of Pasteur. "used cowpox to create a vaccine for smallpox."
"While I am new to your techniques, I have some ideas. Might it not be possible to create a vaccine for the plague using a similar, but weaker illness. Perhaps it might even be possible to develop a cure from such a source of illness. We may be able to strike a blow against this Red Death, that may benefit our worlds and others besides."
"Regardless, the Free Nations of Faerun, appreciate your health. I pray for your well being, your success, and the health and happiness of the peoples of Earth. I promise to devote my resources and give my life, if need be to aid Earth in its own struggles. I hold that all of us, whatever our world or form, are all akin in one family of being. I have heard on other worlds of a High God, the True Creator of All Things. In the name of the Eternal, in the name of all that is good, I beseech your help. And offer mine in return to you, and all the peoples of Earth."