Quite similar to above, the idea of transubstantiation is a distinctly Catholic one, to which I and many other theists do not subscribe. I know some Lutherans, and perhaps other denominations, assert consubstantiation, which means the Eucharist remains fully bread and wine while also being fully Christ — in the same way Jesus of Nazareth was fully man and fully God — but, again, I and many other theists do not hold this view. Therefore, it does not fit in the category of what your story is supposed to be: a list of questions for theists. And because I don’t believe it either, I have no further response.