Whoever told me to add dark chocolate to chili

Don't listen to any r-slurs who tell you to add a "secret ingredient" to chili. Everyone always has one, chocolate is one of them, coffee is another one (for the same reason even) and there are a bunch of other ones, and they're all gimmicks. The only thing you need to do to make good chili is go to this site:

https://www.casichili.net/recipes.html

That's a list of winning recipes from Texas's most famous chili contest. They're all extremely similar to each other, and if there's a "secret ingredient" tying them all together, it's this stuff:

That's labeled "coriander and annatto" which are certainly in there, but the main ingredient in this shit is regular old MSG, and believe me, you will notice a difference if you add that toward the end of cooking your chili. The other thing common among all the Terlingua champions is that they add a LOT of dried spices, and specifically they add more of them right at the end so that the flavor combination is aggressive and in your face rather than the subtle flavor you get from cooking stuff for a really long time.