I'm speculating here, but it seems obvious that material and energy from the star would rush through the black hole's event horizon very quickly. Could this be enough to reverse the process that created the black hole in the first place, or will the entire large star get sucked into the black hole as mass rushes over the event horizon and causes the event horizon to expand?
Granted, the very large star would eventually turn into a black hole itself anyway, so it should be a zero-sum game from a mass perspective. But if a large star can incorporate a small black hole into its own core, then maybe when the large star goes supernova later, some very exotic materials or radiation from the reincorporation of the small black hole would be expelled?
For a size comparison, I'm thinking a star that has one or two thousand times the mass of our sun, versus a black hole that has 4 or 5 times the mass of our sun. Speed and trajectory obviously make a difference. But I'm looking for a situation where they could possibly merge into something stable.