Broken Steel is weird.
It's a decent stab at an Archer origin story in the sense that it tries to fuse together the breadcrumbs that Nasu has fed us, but it has too many hiccups for me to recommend it. A lot of it has to do with the length.
There aren't enough words on the page to explore the son, the relationship or almost any of the things passing between Shirou and Rin. The author devotes an entire section to the final moments of the Grail War, but everything else is rushed into incoherence.
I don't believe that Shirou and Rin loved each other when there is nothing done to show us. I don't see how Rin could forgive Shirou for what he did or how Shirou could bring himself to open up to her after shutting up his emotions in the first place. I don't have much invested in Daiki or his situation when it's all exposited at us so formally. The conversation with Shirou and Rin doesn't flow naturally because the author has to pause every so often to give paragraphs explaining what they're talking about. Here's something that really exemplifies that problem:
Show me Daiki. Show me who he is and why I should care. Putting it as simply as "Their son, their baby boy" is an emotional shorthand for "someone really important you, the reader, are supposed to care about." But I don't care. Daiki doesn't ring true as their son. Daiki is a concept, a device to drive a wedge between them. And all of this after they patched things up enough--somehow--between the Grail War and Broken Steel that it could fall apart all over again. Show me that relationship if it's so important. Give me a series of vignettes, snapshots, slices of life, pieces that come together to form a greater tapestry.“This is for Daiki.”
Shirou froze. Their son, their baby boy, whom he had visited whenever he had gotten the chance, had played with and loved with all his heart — the bridge between the Tohsaka and Emiya families that had, for a short time, allowed him into Rin’s life again—
Until the day the boy decided he would follow his father into the battlefield. One of those stupid accidents, a rogue magus close enough to Rin’s house that a young teenage boy could try and get to the site without even a car — without either of his parents knowing—
There had been so much blood.
bard_linn does entirely too much telling and not enough showing.
And that's because bard_linn seems to treat Broken Steel as a chance to dole out some headcanon instead of weaving it into a real, breathing story. It's self-indulgent.
-1 from me