A black chili can turn red when matured. That's a well-known mechanism according to my wife's aunt, my gardening teacher.
I will set aside some of the fruits for seeding in the next season so it's good for me to see ripen "red black chilies" at this stage.
I wonder if the ripen red one is as hot and spicy as normal normal red chilies. Well, I'll try to taste them in the near future,,,.
-- from iPod touch