In Frankenstein and Dr. Jekyll & Mr. Hyde both think they have control at first. What are some examples of this?
Another similar novel that comes to mind is Dracula. Several characters think they have control at various times in the novel. Jonathan Harker fancies himself an up and coming lawyer (solicitor) when he travels to Dracula's castle on business for his employer. He notices strange things, which he writes about in his journal, but at first he thinks he is safe and in control and perfectly able to leave when he wants to. He soon finds, however, that in reality, he is Count Dracula's prisoner.
Arther Holmwood (later Lord Godalming) believes he is in control when he repeatedly offers his own blood to save Lucy, but he, too, eventually must admit that Lucy has become a vampire and he really has no control of the situation.
The team of men - Holmwood, Harker, Dr. Van Helsing, Dr. Seward and Quincey Morris think they are succeeding to protect Mina for a long time, but eventually even they are forced to admit that they are losing control and in order to save Mina, they must kill Dracula.
The big difference in Dracula, however, is that although the humans also are fighting against an other-wordly being, this being is not of their own creation, such as the Frankenstein monster and Mr. Hyde.