The fact that you started this story in media res meant that the action grips the reader right from the opening paragraph. It's a fast beginning, which slows down as we get to know the characters, and I like that. However, despite the fast pace initially, it's not all mish-mash-mosh - I found a certain pathos in the opening lines when Jason begins to question whether he'll ever get back to see his family.
Your characterisations are strong. I liked Calvin, though I'm not sure whether I should have. Though he was only a cameo in the story, he was vivid and humorous. Jason is very human, thoroughly padded out with detail, and the relationship between him and Myr'yam was believable and touching. The conversation over their names made me laugh.
The descriptionsof the scents and sounds put me right into the scenes you describe - very visual storytelling - and I thought that the description of the lions on the kill, whilst vicious, had a gentleness to it (if this is the right word) that contrasted with the brutality of the conflict around them.
A couple of points: I found the fact Myr'yam collapsed so suddenly a bit confusing. I didn't know if she'd been shot, or just died. It didn't make sense to me when she had been so lively until this point (unless I missed something). Also, the story is very complete, and I think I'd like something left open, something to think about, but that might just be me. I struggle to know in my own stories what I should explain and what I shouldn't at the end.
Fantastic story, really moving, kept me gripped.