In the Fate saga, Enkidu is a shapeshifter. This is because his legend says he was formed from water and clay.
The goddess Ishtar bears the appearance of Rin Tohsaka from Fate/stay night (2006). According to the Fate saga, Ishtar picked Rin's form as she found it the most beautiful.
Enkidu, though a male, has the body of a woman. This woman is Shamhat, in his legend the woman who seduced him and tutored him about human civilization.
Ana in this series is a young Medusa from Fate/stay night (2006). While Medusa is generally Rider class, for this series she appears in Lancer class.