(1)Luna Lovegood
(1)Remus John Lupin
I'll be honest here, I'm biased; I've dressed up as Luna for haloween. There's no way I'm voting for anyone else.
Remus has more character depth, no question. Getting to the point that he talks about abandoning his pregnant wife because he's worried his kids will be better off without him is...pretty dark.
Luna's got more style and humor, though, hands down. Loser's Lurgy.
And...honestly, Lupin's amount of screen time after book 3 is actually a little disappointing. Absent in book 4. Present for a few scenes in book 5, but he's definitely not the top pick for "person to put in a scene at Grimauld Place", but he gets a couple. Then book 6 he has little more than a cameo, and book 7 he has...two excellent scenes, and that's about it. Luna gets a lot of screen time in books 5 and 6, and probably still more than Lupin in book 7. Lupin definitely feels like he could have been improved by giving him a few more scenes throughout his story arc, instead of just snapshots where we're left thinking "oh, married and pregnant; when did that happen?" Luna, on the other hand, is pretty complete as-is.
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Cats land on their feet. Toast lands peanut butter side down. A cat with toast strapped to its back will hover above the ground in a state of quantum indecision