As readers we only know what Harry notices/pays attention to, and although we have no idea what color Cho’s eyes are or what Zacharias Smith’s voice sounds like, we know a lot about Draco Malfoy. Consider. We know:
His hair is blond. But not just blond. It’s a particular, white-blond color that gleams in the sunlight.
And very sleek, but loose enough that it falls around his face if he moves around vigorously enough.
He has grey eyes. Not just grey, but specifically light grey.
Harry also frequently describes them as glittering or sparkling.
He presumably has a sweet tooth as he gets regular sweets packages from home delivered by his eagle owl.
He has very pale skin which takes on a grayish tinge when he’s sickly.
He tends to narrow his eyes when he’s angry.
He doesn’t blush when he’s embarrassed but he does flush - just enough to give his skin a faint pink tinge.
He tends to move his hands a lot when talking animatedly.
His speech has a very specific drawling cadence and tone that makes his voice easily recognizable (to Harry at least).
This is all in canon.
Meanwhile, even though Harry and Ron are together practically 24/7 for seven years, we only find out that Ron’s eyes are blue halfway through Deathly Hallows.
harry never realised that he didn’t know when his parents had died
thinking back, he could remember asking aunt petunia once when he had become an orphan
he had earned extra chores and a trip to the cupboard for that
he was all smiles that first halloween at hogwarts, eager to see what a magical halloween was like
he didn’t understand the side glances he got as he walked into the great hall
ron smiled uneasily at him as he sat, a stark difference from his overwhelming exuberance and enthusiasm just an hour ago
“listen, mate. i’m sorry about earlier… i forgot. you don’t have to go exploring the castle with me if you’d rather.” he mumbles, avoiding harry’s gaze
a flicker of fear stirs in harry’s heart. is this the day that ron decides that harry’s too much of a freak to want to remain his friend? (maybe uncle vernon was right after all, maybe he didn’t deserve to have friends)
harry struggles to keep his voice even “if you have other people you want to be with, you don’t have to spend your time with me. i completely understand.”
ron blinks in confusion, “no i meant today probably isn’t a good day… i mean, it’s halloween surely you…”
“yes i know today’s halloween. what’s special about that?” harry asks, bemused
ron’s eyes widen as he realises something. “don’t you know that your parents died today?” he asks suspciously
and harry just stares blankly at him for a good five seconds before slowly shaking his head. “no… the dursleys never told me… i can’t believe i never knew…”
maybe this explained the funny feeling he got at this time of the year
