“Days of Our Lives” has had its share of villains over the years.

But what’s the story behind Gabi Hernandez’s bizarre pacemaker app?

Why do Gabi and Julie hate each other?

Camila Banus on the red carpet

Gabi and Nick both had a history of past criminal activities, but they seemed to understand each other.

The pair began dating and fell in love and eventually tied the knot.

However, when Gabi rejected him he became very angry.

DOOL stars Camila Banus and Susan Seforth Hayes

He followed her into the woods and attacked her.

Gabi fought back and hit Nick with a rock.

Believing she had killed him, Gabi called in reinforcements.

Camila Banus poses

She, Sami, and Kate later threw Nick’s body into the river, perSoaps.com.

However, Nick wasn’t dead.

Nick died in Julie’s arms.

The murder landed Gabi in prison and Julie never forgave Gabi for killing a member of her family.

Gabi and Julie’s feud later caused a shocking incident that almost cost Julie her life.

It was revealed that she needed a heart transplant to survive, but things were looking grim.

Stefan was rushed to the hospital and his heart was declared a match for Julie.

Lani begged Gabi to do the right thing, and she ultimately signed off on the organ transplant.

Gabi then forced Lani to break up with her fiance Eli Grant (Lamon Archey) and leave Salem.

Julie was stunned that Gabi would sink so low, and she had the pacemaker replaced.