The science ficiton genre seperates itself from other genres (such as western or gangster) in the fact that people grew up seeing all these films and they take on certain "looks" that become the genre. You see a cowboy and know it's a western film, you see Al Capone and know it's a gangter film. Sci-fi films are not as easily "pigeon-holed." You may be able to know the film is in space but the plot and characters can be drastically different, and therefore it may not actually be a science fiction film. The props used such as costumes and weapons also lend to this idea.
In regards to how Hel is regarded in the fantastic context ( between the marvelous and uncanny.) This context is defined as falling outside of the rational or relastic, and this makes sense as making a evil robot "clone" of a woman for the specific purposes of manipulating your son certainly is not realistic by today's technological standards. The book states that "marvelous" deals with the supernatural and "uncanny" deals more with the unconscious mind, so neither of these deginitions would encapsalate the character of Hel/Maria. The fantastic seems to play on ideas that are based somewhat in reality (such as cyborgs and artificial intelligence, things that are in their infancy today.)