I swear I feel physical pain every time I'm reading a fic and Harry says something to Draco like, "You tried to kill Ron!"
A much more accurate, canon-consistent statement would be: "Ron almost died because of you" or "Ron was poisoned as a consequence of your actions."
I'm not trying to absolve Draco of responsibility here. I'm just pointing out the obvious: Draco wasn't actually trying to kill Ron, nor was he trying to kill Katie Bell. Both incidents were the result of failed attempts to kill Dumbledore.
I can absolutely understand Ron making that kind of unfair and mistaken accusation. But Harry? Harry saying it? I swear, that bothers me on a profound level, not even because of Draco, but because it feels so out of character for Harry.
Harry clearly doesn't hate Draco after the war. In fact, I'd argue Harry hasn't even known how he feels about Draco since the Sectumsempra incident. He doesn't blame Draco for Dumbledore's death, and he definitely wouldn't claim that Draco deliberately tried to murder Ron.
Personally, I'm not even convinced Harry fully blames Draco for the Death Eaters' invasion of Hogwarts in HBP. Harry had three separate opportunities to hold Draco responsible for all of this, and he didn't take any of them: first, when he chose not to tell Dumbledore everything he had discovered; then when he gave statements to the Aurors after Dumbledore's death; and finally during the post-war trials. (Curiously, Harry favored Draco in all three instances: first through omission, then by giving a cold, sparse account that left out important details, and finally by deliberately speaking in Draco's favor.)
Now, I completely understand that some writers choose to start their stories from the premise that Harry still hates Draco after the war. That's a perfectly valid narrative choice, and while it's not my interpretation, I can absolutely see why someone might write it that way.
But having Harry say that Draco tried to kill Ron?
No. Harry would never say that.
Please don't take this as a personal attack on anyone. This is just a bit of a rant... and maybe a plea, especially to Drarry writers, to remember that Harry can have resentment, anger, guilt, and all sorts of complicated feelings about Draco and his actions during the war without actually hating him.