Question: What One Direction member helped write Just Hold On?

Context paragraphs:
Take Me Home (One Direction album): Take Me Home is the second studio album by British-Irish group One Direction, released on 9 November 2012 by Syco Music and Columbia Records.  As a follow-up to One Direction's internationally successful debut album "Up All Night" (2011), "Take Me Home" was written in groups and has an average of just under five songwriters per track.  Largely recorded and composed in Sweden during 2012, Savan Kotecha, Rami Yacoub and Carl Falk, who composed One Direction's hits, "What Makes You Beautiful" and "One Thing", spent six months in Stockholm developing songs for the album, and were able to shape melodies around the members' tones.

Moments (One Direction song): "Moments" is a song by English-Irish boy band One Direction from their debut studio album, "Up All Night" (2011).  It was written by Ed Sheeran, and Si Hulbert, the song's producer.  In 2011, as One Direction member Harry Styles told Sheeran that the boy band did not have enough songs for their album, Sheeran offered "Moments" as a track that Sheeran "was never going to use".

One Direction: This Is Us: One Direction: This Is Us is a 2013 British-American 3-D documentary concert film centering on British-Irish group One Direction.  It opened in the United Kingdom on 29 August 2013, followed a day later in the United States.  The movie shows many clips and songs of One Direction.

Liam Payne: Liam James Payne (born 29 August 1993) is an English singer and songwriter.  He rose to fame as a member of the boy band One Direction.  Payne made his debut as a singer when he auditioned for the British television series "The X Factor" in 2008.  After being eliminated as a solo performer, he auditioned again in 2010 and was put into a group with four other contestants to form One Direction.  One Direction has released five commercially successful albums, performed on four worldwide tours, and won multiple awards.

Midnight Memories: " Midnight Memories" is the third studio album by British-Irish boy band One Direction, released on 25 November 2013 by Columbia Records, Syco Music and Sony Music.  The album was described as having a "slightly rockier tone" than their previous efforts.  It has become the fastest-selling album in Amazon UK's history, breaking the record set by One Direction's previous release, "Take Me Home" (2012).  The album debuted at number one on the US "Billboard" 200, making One Direction the first group in history to debut at number one in the US with their first three albums.  The album was preceded by the release of the singles "Best Song Ever" and "Story of My Life".

As the City Sleeps: As the City Sleeps is the debut album by gothic rock band Mary and the Black Lamb.  The album is about different experiences the band members have gone through.  Most of which are based on true stories.  All the songs on the album were written by Lindz Riot with the exception of, Stranger where Matt Kelly helped write and arrange it, and Silence which Nixon helped write.

Only One Direction: Only One Direction is an international production and theatre show about English-Irish boyband One Direction.  The band has performed to hundreds of thousands worldwide.  In October 2015, Only One Direction - The One Direction Story opened in London's West End.

Just Hold On: "Just Hold On" is a song by American DJ Steve Aoki and English singer and songwriter Louis Tomlinson, released as the latter's debut single on December 10, 2016, by Ultra Music.  It was written by Tomlinson, Aoki, Eric Rosse, Sasha Sloan and Sir Nolan and produced by Aoki, Sir Nolan and Jay Pryor.  Aoki and Tomlinson performed the song for the first time on the series finale of "The X Factor" (UK).

Louis Tomlinson: Louis William Tomlinson (born Louis Troy Austin; 24 December 1991) is an English singer and songwriter.  He is known as a member of the boy band One Direction.  Tomlinson began his career as an actor, appearing in ITV drama film "If I Had You" and the BBC drama "Waterloo Road".  In 2010, he became a member of One Direction after being eliminated as a solo artist on the British music competition series "The X Factor".  Tomlinson is one of the main songwriters of One Direction's repertoire.  Following the band's hiatus, Tomlinson released the singles "Just Hold On" and "Back to You".  The latter will be included in his debut studio album, which will be released in 2017 by Epic Records.

Up All Night (One Direction album): Up All Night is the debut studio album by English-Irish group One Direction, released by Syco Records in November 2011 in Ireland and the United Kingdom, followed by a worldwide release during 2012.  Four months after finishing third in the seventh series of British reality singing contest "The X Factor" in December 2010, One Direction began recording the album in Sweden, UK and the United States, working with a variety of writers and producers.  The album is predominantly a pop music album which orientates into pop rock, dance-pop, teen pop and power pop.  The album's lyrical content regards being young, relationships, heartbreak and empowerment.  Staged in support of the album, One Direction performed the album's songs live on televised shows, at awards ceremonies, and during their worldwide Up All Night Tour.

Supporting paragraphs: Just Hold On Louis Tomlinson
Answer: Louis Tomlinson