weird thought: what if the engines have memories, have experiences, have thoughts and feelings, and can actually control themselves to some degree, but gain their faces at different times? this therefore prevents the engine from obviously having a face, making facial expressions, facial features, etc., but also from speaking- they cannot speak without their faces, and without this, their drivers and firemen won't know directly if there's actually an issue with the engine. what if james and henry were some of the few engines to get a face very soon following being built, hence leading to henry constantly being aware of when something's wrong with him, while also explaining the wrinkles on james' face. or engines like thomas and percy instantly getting a face after their smokeboxes being put together, leading them to have freshly brand-new opinions and feelings to express without actually having experienced anything. or even edward (our favorite shy steamer- might have to do with this), duke and emily (being some of the oldest by basis) being full in steam longer ago, but not having gained faces until almost a decade or two later- something that could actually tie in to duke's old spiel of "back in my day, engines were seen but not heard."