After reading parts of the chapter twice, it seems to me that Kurosaki Mari received her blessing of immortality from an agent that's opposing the one who summoned Almus and gave him his blessing. That's rather interesting. So, basically Meelin and Almus aren't enemies, but their backers possibly are. That might lead them to try to destroy each other. Although, as expected after 500 years of life, it seems to me Meelin isn't willing to dance to someone else's tune. But she also isn't going to let anyone stop her from achieving her own goals.