"My Songs Know What You Did in the Dark (Light Em Up)" is a song written and recorded by American rock band Fall Out Boy, released as the lead single for their fifth studio album, Save Rock and Roll. It serves as the band's first single following their three-year hiatus and regrouping in early 2013. The track and its music video were released on February 4, 2013 worldwide and February 5, 2013 in North America, to coincide with the official news of the band's reformation. The band felt that the song best represented their album at its core.
The song's title and principal lyric originate from an unrelated 2004 demo by the band. Fall Out Boy performed "My Songs Know What You Did in the Dark (Light Em Up)" on Jimmy Kimmel Live! for their first post-hiatus TV performance on February 13 as well as on various TV shows throughout the entire year, and have extensively played it in acoustic version at radio interviews. Lead vocalist/guitarist Patrick Stump performed the song as a guest on Taylor Swift's Red Tour on July 13, 2013, and Swift guested in turn with Fall Out Boy on Victoria's Secret Fashion Show on November 13, 2013. The song became a staple at several sports-broadcasting soundtracks that year.
The music video is part 1 of The Young Blood Chronicles, a series in which a video was eventually recorded for every song on Save Rock and Roll as part of a narrative. "My Songs Know What You Did in the Dark (Light Em Up)" was a comeback success, reaching the 2 million digital downloads mark in July 2013, being the fourth song by Fall Out Boy to do so, and was certified 3x Platinum by the end of the year. It was named by BBC Radio 1 as one of the "Top 100 Tracks of the Past 5 Years" and No. 1 on Sirius XM Hits 1's best of 2013 countdown. It reached the top 10 on both Pop Songs and Alternative Songs with heavy airplay, and peaked at No. 13 on the Billboard Hot 100 with twelve consecutive weeks in the top 20.
The music video for the song is the first of the Young Blood Chronicles, an ongoing series with the band filming a video for every song on Save Rock and Roll. It begins late at night, with a figure - later revealed to be rapper 2 Chainz - walking away from a black van parked in a forest clearing. He starts a bonfire by pouring gasoline over a wood pile and lighting it up with a match. Two women then exit the van, carrying various music instruments belonging to Fall Out Boy which they then toss into the fire. Among the items they throw in are the band's guitars, a bass, drumsticks and various drums and cymbals. They also throw in amplifiers and Fall Out Boy records such as Take This To Your Grave, From Under the Cork Tree and Live in Phoenix, along with a Fall Out Boy wristband and Fall Out Toy Works comics. 2 Chainz then uses a flamethrower to speed up the incineration process, while the women return to the van and open its rear doors, revealing four hooded, bound men that are implied to be Fall Out Boy themselves. The camera then closes in on 2 Chainz's face as he holds up a match and stares at the band menacingly, ending the video.
Fall Out Boy's capture is shown in the music video for the following single, "The Phoenix", released on March 25, 2013.
Commercially, "My Songs Know What You Did in the Dark (Light Em Up)" debuted on charts worldwide with success, reaching in the top five in the United Kingdom, charts the band have previously received success from with singles like "This Ain't a Scene, It's an Arms Race" and "Thnks fr th Mmrs".
On the U.S. Billboard Hot 100, the song debuted at number twenty-six and number eight on the U.S. BillboardRock Songs chart; it reached number two on iTunes upon its release with 162,000 first week sales. In its nineteenth week on the chart, it reached a peak of number thirteen on the Hot 100 and number two on the Rock Songs chart (upon Save Rock And Roll's release). The song has sold over 3 million downloads in the United States by February 2014, the first song by Fall Out Boy to reach this level.
"My Song Knows What You Did in the Dark" was featured in the promotional video for the backdoor pilot of The Originals and during the Starz programming lineup.
The song was also used during Timber Brown's acrobatic act during the quarter finals on season 8 of America's Got Talent, the show which Fall Out Boy would later perform the song at with "Alone Together" leading in.
The song was used for the trailer for Disney's Big Hero 6, which featured the band's song "Immortals" in the film.
The song was used for the soundtrack to the video games NHL 15 and Guitar Hero Live, the latter appearing as a playable track.
A remix, produced by Wonder Arillo, featuring rapper 2 Chainz with hip-hop sound was released on April 3. It was performed live the month before by Fall Out Boy and 2 Chainz at the beginning of the 2013 NBA slam dunk contest.