How to Train Your Dragon is a series of twelve children's books written by British author Cressida Cowell.
 The books are set in a fictional Viking world and focus on the experiences of protagonist Hiccup as he overcomes great obstacles on his journey of Becoming a Hero the Hard Way.
 The books were published by Hodder Children's Books in the UK and by Little, Brown and Company in the US.
 The first book was published in 2003 and the last one in 2015.
 As of 2015, the series has sold more than seven million copies around the world.
Shaken is written by "Jerry B. Jenkins" and "Tim LaHaye", bestselling Christian authors.
 It covers books 23-25 of the series, which tells about the 7 years before the Glorious Appearing of Christ.
 It is book seven of the twelve book series.
The Vampire Huntress Legend Series (VHL) is a twelve book series written by Leslie Esdaile Banks under the pen name L.A. Banks.
 The series centers around a young "twenty-something" woman named Damali Richards who is a spoken word artist but is also the Neteru, a human who is born once every thousand years to fight the Dark Realms.
 Her most dangerous and most constant enemy from The Dark Realms are vampires.
Demon Thief is a book in Darren Shan's "Demonata" series.
 Though it is the second book in the series, it is a prequel to "Lord Loss", the first book in the series.
 The protagonist is also different from that of the first book.
 The narrator here is a new character called Kernel Fleck, as opposed to Grubbs Grady, the protagonist of the first book.
 Demon Thief takes place about thirty years before "Lord Loss" so most of the characters from the first book did not appear, though a few did.
 It was also actually the sixth book of the Demonata to be written, although it was the second released.
Joris Oprins (born 1980, Tilburg) is an animation director.
 He studied at the Design Academy Eindhoven in the Netherlands.
 He graduated in 2003.
 In 2005 he worked as an animator on the stop motion children series Miffy at studio Pedri in Ankeveen.
 In 2007 he co-founded animation studio Job, Joris & Marieke together with Job Roggeveen and Marieke Blaauw.
 Job, Joris & Marieke works on commissioned work, music videos and short animated films.
Among the Free is a 2006 book by Margaret Peterson Haddix, about a time in which drastic measures have been taken to quell overpopulation.
 It is the seventh and final book in the Shadow Children series.
The Glitch in Sleep is the first novel in The Seems children series, released as a hardcover on September 18, 2007 by Bloomsbury Publishing.
 It was written by John Hulme and Michael Wexler.
 The book follows Becker Drane, a Fixer for The Seems on his first Mission to find and capture a Glitch.
 The Seems is a parallel universe in charge of providing our World with what it needs to keep on going.
Louie del Carmen (born August 19, 1967) is an American animation storyboard artist/director and illustrator.
 Born Manuel Luis Gonzales del Carmen in Cavite City, Philippines, he began work in the mid-1990s on animated series like "Rugrats", "Rocket Power", "Invader Zim", "The Grim Adventures of Billy and Mandy", "Kim Possible" and "The Mighty B!
".
 During the summer of 2007 he began working as a story artist at Dreamworks Animation on some of their notable and successful projects like "Kung Fu Panda", "How to Train Your Dragon" and "The Croods".
Protected is a Christian novel by Jerry B. Jenkins and Tim LaHaye.
 It contains titles 32-34 in the series.
 It's also the tenth novel in the twelve book series.
Hunted is a novel written by Jerry B. Jenkins and Tim LaHaye, who are both Christian authors.
 "Hunted" covers titles 35-37 in the series.
 It is also the eleventh novel in the twelve book series.
 It starts when cruel Bounty Hunters kidnap Judd Thompson Jr., Lionel Washington, and Tom Gowin, planning to bring them to the Global Community and receive a reward.
 The fearless Christians escape their kidnappers and flee to a nearby safe house.
 Judd and Lionel long to travel to Wisconsin and see their friends again, but the new Bounty Hunters looking for money stop them from going anywhere.
 Finally, they come up with a plan to travel to different safe houses on their way to Wisconsin, slowly getting closer to their friends.

Question: What twelve book children series was started during the summer of 2007 and the first book was publisehed in 2003?
Answer: How to Train Your Dragon