Morty and Mr. Dhondt are two of Ayrs's friends. Although their main purpose seems to be to drive the plot (almost literally—both of their major scenes involve them driving Frobisher somewhere in their car), Morty Dhondt also drops a few bombs of wisdom on our dear Frobisher.
On the way back from the cemetery where Frobisher's brother was supposed to have been buried, Morty, after accidentally running over a giant turkey, puts the novel's endgame into words: "Our will to power, our science, and those v. faculties that elevated us from apes, to savages, to modern man, are the same faculties that'll snuff out Homo sapiens before this century is out!" (10.1.19). Yep, that's pretty much the whole point of the final half of Cloud Atlas. We couldn't have said it better ourselves. Do you think he's being cynical or realistic?