Toxic_Nutella's "Barbie" is a bitter address to someone who hurt the speaker after seeming to care. The opening lines set up the betrayal: the person promised to help, then left the speaker crying and collecting the pieces of a broken heart. From there the speaker moves between anger and hurt, demanding an explanation and accusing the other person of building them up only to tear them down.
The doll imagery carries the main idea. "Plastic love," "plastic hearts" and "fake as a Ken doll" suggest affection that looked perfect but was hollow. The speaker also describes themselves as barbed wire against the other's wildfire, which hints at a guarded person facing someone destructive. The tone is raw and sometimes threatening, with warnings that the other person's "reign" could end. The final lines turn quieter and sadder: the speaker regrets offering something real in return for something fake.