Didn't expect them to be related, and man things are looking bleak. D:
I love how much interesting info we get this chapter from these 2 and how intense this chapter was. If he did change from breath of the sun to breath of the moon I could see that making sense. I mean he does look like an original member. Though Zenitsu's opponent was a demon slayer before getting turned and kept his original breath form. Maybe we will learn more on that next chapter. I can't wait!