One of my favorite series is Heather Sparrows Ichabod and the Hessian - which is primarily Sleepy Hollows, but which also features Klaus and Dorian when one of Klaus's missions takes him to America. James in good shape.
I also love The Snitch and the Bludger by Laura Kaye, with 11 year old Klaus taking the Hogwarts express and on the train he meets a British boy, Dorian. It's just so sweet and I would love to read more in this universe.
TelWomans The Colour of Polished - crossover with Back To The Future - just a lovely idea for a crossover and several neat details.
Lately also The Hatchling Job, by Sholio, a crossover with Pern where K'laus is a bronze rider and Dorian really want to impress a golden dragon ... Sweet story that made me smile.