Jack "J.J." Deveraux Jr. is a fictional character from the original NBC soap opera, Days of Our Lives.

JJ's first significant storyline launched in 2013 and focused on his rebellion following his father's death and his feud with his mother's new boyfriend, Dr. Daniel Jonas.

Further relationships have included Gabi Hernandez (Camila Banus) and Lani Price (Sal Stowers).

Moss' performance has been met with critical acclaim, having garnered him a Daytime Emmy Award nomination for Outstanding Younger Actor in a Drama Series in 2018.

[1] Casey Moss first auditioned for the role in October 2012, and screen tested with Melissa Reeves, who plays Jennifer Horton, in November.

[16] Moss's JJ was described as Jack and Jennifer's "troubled teenage son,"[17] who returns from boarding school in London with a chip on his shoulder.

However, JJ does not have to worry about forming a "real bond", Moss told Soap Opera Digest.

Abigail is immediately concerned but JJ resents his sister and mother as "he doesn't feel they grieved his father's death."

Though Jack wasn't always physically present, JJ felt a "sense of security" knowing his father was at least out there somewhere.

JJ's lies quickly catch up to him when his school reveals that he was expelled due to him knowing about his roommate selling drugs on campus.

Paige starts to suspect that JJ is dealing and even confronts his mom, who denies it, as she is aware he is working for the DEA.

Clyde then gives Roman false information that he saw Chad outside Paige's dorm building around the time she was killed.

Things take a worse turn when he shoots his girlfriend's brother Theo Carver and gets suspended and charged.

Unable to deal with the guilt of shooting Theo who sadly slipped into coma, he breaks up with Lani.

He then learns that she is pregnant, but wrongly believes the baby is his, when in fact it is Eli's after their one night stand on the Christmas Eve.

In December 2018, JJ comes to the aid of Haley Chen, a nurse at University Hospital, who attempted suicide.

When she is eventually arrested, JJ pleads for Haley's forgiveness and in an effort to make up for the mistake, JJ offers to marry Haley in order to help her avoid deportation; she declines the proposal and marries Tripp Dalton instead in order to get a green card.

Michael Fairman described the character's return as "long-awaited" and said Moss would "add to the young hunk quotient in Salem!

"[25] Jillian Bowe immediately hoped that Moss's JJ would cause trouble for Jennifer and Daniel.

"I absolutely love it when he gives Jennifer and Abigail grief for being able to so readily replace Jack with Daniel," remarked Giddens.

Giddens hoped JJ would cause even more trouble by "hooking up" with Jennifer's rival, and Daniel's ex-wife, Chloe Lane (Nadia Bjorlin).

[27] Laurisa Mahlin of Soap Central praised the dynamic in contrast to the usual romantic triangle for Dannifer.

Mahlin explained that even though JJ is acting horribly, it was enough for most fans that he caused trouble for the hated pairing.