Regarding the thumbnails for that shot, I thought A was more "badass" but made the lady of the Lake looks almost like a threat. I mean I still wanted her to look intimidating but not that threatening haha ! When I posted these 2 thumbnails on my instagram stories, the majority of people voted for thumbnail B, which is quite flat honestly but the relationship between the characters is a bit stronger in my opinion and it is way easier to see the size difference.
I wanted the Lady of the Lake to look like a water spirit, just like Merlin is more of a Forets Spirit in my project, rather than a wizard. While Merlin does more effort to "look human" because he is more in contact with them, the Lady of the Lake doesn't really care if her appearance is pleasing to the humans or not. As a kid I love the animated movie Sinbad and I remember that the design of the mermaids in this animation were just genius and the best design I ever seen for such creatures. I wanted to reuse the design solution of having a body made out of water because it is not something I remember seeing that often. the only other character design I can think about with that design solution would be the water horse spirit in Frozen 2.