Both Frankenstein and Never Let Me Go, though separated by nearly two centuries in publication, deal with unethical or irresponsible uses of technology. Also, both Mary Shelley and Kazuo Ishiguro structure and narrate their novels in interesting, thought-provoking ways for various effects.
Frankenstein is a frame narrative and an epistolary novel. The frames consist of a series of letters from Robert Walton to his sister, Mrs. Seville. We see this letters at beginning and end, while the story of Victor Frankenstein is contained within those letters, as Victor told his story to Robert. Further, the innermost frame of the novel is Frankenstein's creature narrating his own experiences once Victor has abandoned him.
The frames and the letters alter the reader's perception of the characters, namely Victor. The outermost frame shows us how a stranger initially reacts to Victor (he is very sympathetic) and almost mirrors how we will first see Victor when he tells of his childhood and education. The Walton frame also allows us to see how Victor's story changes Walton's mind about his ambitious mission to the Arctic; he has seen the danger of excessive ambition and thinks better of the mission for the sake of his men. Victor, on the other hand, created his monster without sufficient forethought and for selfish glory.
The innermost frame of the novel, the creature's story, certainly complicates our sympathy for Victor and leads most readers to side with the creature, who has been greatly wronged by his creator. The creature's story suggests that he was "born" good and only became evil through the mistreatment and rejection of others. The frames mitigate the first-person narrative by Victor and give us other contexts by which to judge his actions and his version of the story.
Never Let Me Go does not have as complex a structure as Shelley's novel, but the narrative voice is very important to the way the story unfolds. Kathy is the narrator, and she is also one of the "creations," genetically engineered to one day donate her organs to "regular" humans. These people are basically clones, and while they grow up with a somewhat normal life, in young adulthood they transition into roles as donors or carers, until they "complete."
The narrative choice to have Kathy tell the story means that she only has limited knowledge of the genetic engineering and can really only guess at its motives and suggest its potential outcomes. We hear the story of her life from early in her time at Hailsham, a boarding school for the donor children. While there is some mystery, Kathy's lack of information creates suspense for readers, and the big reveal comes as quite a shock to both character and audience.
As Kathy struggles with the meaning of her own life and those of her friends, and as she desperately tries to find a "way out" of her fate, we follow her agonizing emotional rollercoaster. Therefore, Ishiguro's choice of narrator and the suspense created by the way she tells the story definitely impacts the revelations we see and how we react to them.