Sophia is right, there’s no hint that it’s incest except for the challenge. I like your use of italics except for the word constricting. For some reason, I didn’t feel that word needed it because it’s such a strong word. But a good entry!
Actually no, the only editing I did was with the word ‘constricting’. I read over the comments and agreed with Horrorfan13. Thanks for seeing the connection between the blood and the brother/ sister relationship though—that’s what I was going for!