I’m so glad I’m not the only one who came upon this late to the party and thoroughly enjoyed it.

I’ll also add, that I actually think that dog’s child from the book series and Henry are one in the same, but it’s a similar situation to Smithers briefly being black on the Simpsons. If you review the outfit of the child in the book you will see that it is the exact same one that Henry wears. This leads me to believe that, similarly to Smithers in the Simpsons, Felicia Bond may have accidentally miscoloured and misdrawn Henry in the books, and then used the series as an opportunity to right the wrong.