Place the butter in a small skillet. Split the vanilla bean and scrape the seeds onto the butter. Mash seeds into the butter with the back of a spoon. Add the scraped pod and melt the butter over low heat. Remove from heat and set aside to steep.
Heat the coconut cream and heavy cream in a small saucepan over medium heat until simmering. Remove from heat and stir in chocolate until melted and smooth. Stir in the lime zest. Set aside. (The vanilla butter and chocolate sauce can be made up to 3 days ahead, refrigerated, and reheated before grilling.)
If using wooden skewers, soak them in water for 30 minutes before grilling. Prepare an outdoor grill with a low-medium fire.
Prepare the fruit for the skewers, cutting the fruit into 2-inch chunks. Thread the fruit onto 8 (8-inch) skewers, alternating the mango and papaya. Brush lightly with some of the vanilla butter. Grill the fruit until lightly charred but not mushy, turning as needed, about 5 minutes per side. Pool about 2 tablespoons chocolate sauce on each of 4 plates, arrange 2 skewers on each plate, and drizzle with a bit of vanilla butter.