Combine pineapple juice, brown sugar, soy sauce, sriracha, garlic, and red pepper flakes in a bowl until the sugar dissolves and the mixture looks glossy. Visual cue: you should see evenly distributed red pepper flakes throughout the liquid.

Reserve 1/4 cup marinade, then pour the rest over the chicken to coat all sides. Visual cue: the chicken should be fully covered, with a deep caramel-brown color clinging to the surface.

Marinate the chicken for 1-2 hours at cool room temperature or in the refrigerator until ready to grill. Visual cue: the chicken surface looks slightly darker and more tacky from the sugar and seasonings.

Preheat the grill to medium-high heat. Visual cue: the grates should be hot enough to make a quick sizzle when the chicken is placed.

Grill the chicken for 6-7 minutes per side until the internal temperature reaches 165°F. Visual cue: visible char forms on the outside while juices collect near the edges.

Brush the chicken with the reserved marinade during the final minutes so it glazes without burning. Visual cue: the surface becomes shiny and caramelized.

Thread pineapple chunks onto skewers. Visual cue: leave small gaps between pieces so they caramelize evenly.

Grill the pineapple for 2-3 minutes per side until caramelized. Visual cue: you’ll see browned edges and syrupy spots on the fruit.

Serve the chicken topped with grilled pineapple, then garnish with cilantro and lime. Visual cue: bright green cilantro and fresh lime contrast the caramelized chicken and charred pineapple.