There are a lot of different ways to come up with a recipe. You can try to replicate one you try at a restaurant, or give a group of ingredients you love a difference spin (For instance, I dare you to find a scenario where Caprese doesn't work: pasta, sandwiches, alone, it's always awesome), or sometimes you treat it like a math equation. If x and y are both delicious, then z will be awesome (given that x + y = z). I mean, I wouldn't try it with roast chicken and chocolate cake, but with roasted pineapple, jalapeno, and citrus, yeah, the math comes out alright.
It's about understanding balance and what "goes." Sort of like how Jonathan Adler can merge 70s tackiness with Palm Springs and it looks amazing, or JCrew mixing plaids. Sweet with acid and spice always works. It's always exciting, and I'm yet to meet someone who doesn't like that combination. Slam dunk, every time.
This is one of those situations. It could've just as easily been mango lime with thai chili, or pear lemon and ginger, so if you're feeling creative, go for it! Come up with your own "perfect" combination. Enjoy! 
For 1 quart (4 cups)
Preheat oven to 450 F. On a sheet pan, lay down the pineapple and half of the sliced jalapeno. Roast until the pineapple is browned at the edges. A few black spots aren't a bad thing. Pop 4 of the roasted pineapple rings and half of the roasted jalapeno into a blender, and puree. Add water if needed to help the blender get going. Strain into a pitcher. Juice the lemons and limes, and put all of the used halves into a bowl and cover with 2 cups of hot water. Let it sit for about 10 minutes. The hot water pulls all of the natural oils out of the citrus skins and adds so much flavor. Add the water and juices to the pitcher, and finish with the agave nectar. Add the remaining pineapple and sliced jalapeno to the pitcher to add color and texture. Chill in the fridge until ready to serve.
