In the manga, Cain Nightroad seems to be very concerned for Abel Nightroad’s well being for reasons unknown. He showed great happiness when he was told by Isaak Fernand von Kämpfer that Abel is well after his confrontation with Dietrich von Lohengrin in the Byzantium nuclear launch facility. Deitrich did mention during the fight that “a certain someone” would be furious if her were to kill Abel.
I guess we’ll never know the real ending for the series, seeing the original novelist, Yoshida Sunao, passed away before he could write the ending. Such a shame. Awesome cosplay by Stay as Cain, but I unfortunately don’t know who is with her. Thanks again to Ophelia for sending this in!