>>3852887I think one of the biggest differences between book Lupin/marauders-era characters and how they were portrayed in the movies was that the movies aged them up about 20 or so years. James and Lily were 20 when they had Harry, and they died when they were 21. Snape should have been 31 in his introduction in the first book, and Lupin and Sirius were both 33 in PoA.
The book description of Lupin says he was "quite young", and that despite this he had flecks of gray in his hair. He is said to look ill, exhausted and pallid, with shabby robes. David Thewlis wasn't a bad pick considering, but I always felt his weak jaw, stringy hair and mustache gave him creepy vibes that would make him unpopular with children, when Lupin was supposed to have been one of the most beloved professors in Hogwarts. The popular "fancast" for a young Remus is Andrew Garfield, specifically as he appeared in the 2010 movie Never Let Me Go.
Book Sirius, on the other hand, was emphasized as having been a former heart-throb, but 12 years of Azkaban left him haunted, malnourished and prematurely aged. Out of all of the characters in the books, Sirius gets called handsome the most. Like, JKR basically trips over herself every time Sirius is mentioned to bring up how good-looking he is, especially in flashbacks and photographs of him when he was young. Gary Oldman is a terrific actor, but I don't think he brought that dimension to the character. The popular "fancast" for a young Sirius is Ben Barnes as he appeared in the 2009 adaption Dorian Gray.