There’s a lot to like here. I can tell the author has put a great deal of thought into all the elements, from prose style to worldbuilding to characterization. The present tense doesn’t get in the way for me; it’s neutral, neither inappropriate nor intrusive. Nor am I perturbed by “non-typical” phrasing, though the intro led me to expect more of it than I found in the ms.

I do wonder somewhat about the cosmic rays. They come across to me as a placeholder: a general term for phenomena that might be described more specifically by an expert in the field. A layperson might use the generic term, but an expert would break it down into components, and talk about those components, as he tries to figure out what is happening and how and why. It’s one of those things that makes the difference to a reader between “author threw in concept to make story go” and “author knows a lot about concept and is dropping in a few key details that indicate the breadth and depth of his knowedge.” These details don’t need to be numerous. Two or three will do it, if they’re the right ones.

In terms of plot and characters, kudos for making a genuine effort to portray diverse characters, and what’s more, to tell the story through, and about, a disabled protagonist. Both of these are not easy to do.

The hard part when writing outside the white-male-cis-het-USian box is to know how to describe characters, both physically and in in terms of their linguistic and cultural context. The tendency to view white-male-cis-het-USian as default means that sometimes a writer tries a little too hard to make it clear that the character is not one or more of these things. So, here, we’re told frequently that both Davis and Singh are not white, that their skin is dark. On the one hand it’s good to address the tendency to view a character as default-white, but on the other, does the reader need to be reminded as often as she is here? Or to put it another way, would a white character’s skin color be referenced as often as these characters’?

I would suggest reviewing Singh’s portrayal in general and watching for racial and cultural stereotypes. He smiles a lot, and he’s quite ingratiating, which is a trope often applied to marginalized and colonialized characters. Add this to the fact we’re reminded so often that he’s Other, he’s non-default in his dress and skin tone, and the overall effect may actually undermine the attempt at diversity. Default is still white and USian, and that’s the perspective of the narrative, even though the viewpoint character is nominally non-white.

Female characters can trip up a writer as well. There’s a lovely lack of male gaze in the description of Caroline—she’s not sexualized, she’s described as she is, and while she’s not likable, that’s fine; neither is Davis. But the unnamed woman in the final scene leads with her breasts. Male gaze, like white gaze, is persistent, so much so that it creeps in even when a writer is trying deliberately not to do it. My question here is, does the woman really need to be sexualized? If so, why? Is the answer to what question essential to the development of the story? And can we get a sense of this in the narrative?

Finally, Davis is a disabled man, and his disability is a key element of the plot. I think it’s smart to portray him as a cranky bastard who became disabled as an adult and has spent much of his life trying to become non-disabled. So much of disability narrative is either inspiration porn or miraculous-cure fantasy. For actual disabled people, this is rage-inducing.

But, I think Davis just about gets away with it. The way he’s framed, the needs and emotions that drive him, make it work. I like the fact that the cure is anything but instant, and that when he finally does get it, he has to seriously work at it. That’s good.

There are stylistic and copyediting bits that I could quibble—length of paragraphs, choice of words and phrases, the location of a frown (no, it’s not the mouth, it’s the forehead and eyebrows)—but I think at this stage it may be more useful to focus on the underlying racial, cultural, and gender assumptions, and to work on fine-tuning those. The will to do it is clearly there; it’s just a matter of going deeper and paying closer attention to default assumptions.