Chris Columbus is getting into the young-adult fiction market with a new series from HarperCollins, “House of Secrets.” The trilogy will be written with YA writer Ned Vizzini and published by HarperCollins Children’s Books’ Balzer + Bray imprint.Vizzini’s “It’s Kind of a Funny Story” received a bigscreen adaptation from Focus in 2010; “House of Secrets” will be a fantasy series focusing on a family that moves to a house built by a fantasy writer interested in the occult. Children’s fantasy is familiar territory for Columbus, who helmed the first two “Harry Potter” films. It’s shaping up to be a busy year for the writer-director, who is also developing a reboot of Western series “The Rifleman” at the Eye. Children’s fantasy lit has proved profitable for many publishers and studios since the “Potter” phenom boosted the genre into the spotlight; Columbus has made Rick Riordan’s “Percy Jackson and the Olympians” series his main post-Hogwarts fantasy enterprise, but film options aren’t the only way for the flagging book industry to capitalize on YA fantasy. The ink-and-paper (and ebook) editions have also helped many publishers amortize the costs of less immediately profitable literary fiction lines all by themselves. “House of Secrets” has already been sold in 12 different foreign territories; the U.K. and commonwealth rights have been acquired by WME lit agent Cathryn Summerhayes’ publishing director Rachel Denwood. The agency’s Dorian Karchmar negotiated the HarperCollins deal with Balzer.