I'll say this from what I can see so far,
1. valkirya sho wants to kill,
2 val wants to destroy cronos
3.ella seeks not only to avenge his brother against his murderer
also against the organization that started the problem
ended up killing his brother
4 for valkirya there is no end in which I think she wins
waiting to die after serving his mission
and with respect to the slowness of the manga, I think it is justified and in fact I'm glad that you take the time to have such quality in the drawing rather than a boring generic precentar sloppy and cliche,
thing you see in weekly sleeves as naruto, bleach, fairy tale, but among others,
I know it's maddening slowness if at least 2 chapters per month were less exasperating serious but I think the fact that I either monthly not only justified by the quality of drawing but if it becomes a weekly, some readers might bore new, and old alike.
do not misunderstand me I want more chapters but as the saying goes. all good in moderation