Fred and George Weasley King's Cross Sweaters, Sorcerer's Stone

We meet Fred and George in dark grey/blue mock turtleneck sweaters. While definitely not the last time the twins will dress alike (and use it to their advantage), it is our first time seeing them, together or apart, and we are met not with their sameness, but their trickster nature.

The sweaters the boys wear have raglan sleeves and a mock turtleneck, making them similar to - although not identical to - the traditional "Weasley sweater" all of Molly's children will wear time and again in the series.

While I didn't find a pattern specific to the twins' sweaters, I did find three sweaters whose construction is so similar as to be used easily for these sweaters.

Big Kids Bulky Mock Turtleneck, by Amy Thompson (free Ravelry download)
Firenze, by DROPS Design (free on the DROPS website)
Purl Soho Pullover, by Purl Soho (purchase the pattern on their site)

Image Source: Home Of The Nutty (some images have been cropped)