Another very good story! I enjoy how you've done it from a child's point of view, and very realistically, too. Poor kid, having to be chained up when he gets older... :( The scene-setting and tone of the story were very well conveyed, and the characters were believable. If I were to offer constructive critisism, it would be mostly mechanics.
---Maybe when Papa teaches him how to fly, he could fly up there on his own broom.---
"teaches" ought to be "taught" to fit in with the same past tense.
---But … if I’m real quiet, as quiet as Mr. Jinx, their kitty cat, maybe they won’t see me.---
Another tenses conflict... "their kitty cat" doesn;t fit with the first-person POV of the thought... Remus already knows Mr.Jinx is their cat, he woudln;t have to clarify it to himself. Would it be possible to mention the cat when Remus is thinking about the fish? Or perhaps afterwards when talking of how the cat walks? The only other thing i would mention is over using the phrase "little boy". I do that a lot myself when I write about children (which I write about often!)
Man, Roman is a little creep! Poor Remus.... Did you omit Remus's age on purpose? I know it never says in canon how old Remus was.
Actually, I think in HBP, it states he is five, but my book is downstairs LOL. I had in mind for him to be much younger in this story -- 2 or 3. This was written before HBP.
Thanks for the review, and pointing out the goofs!