The following article contains an answer for the question: How is the person with a mischievous personality related to Nancy? , can you please find it? 

Robins plays bumbling mad scientist Nathaniel Pickman Wingate, of the Miskatonic University. He works on opening a portal to another dimension while his wife, Nancy and family prepare his fiftieth birthday party.  When he succeeds with contact with the new dimension, two triops-like creatures escape. These creatures possess shape-shifting abilities that allows them to assume the form and identity of anything, and thusly do so with Nancy's cousin, Count Desmon of Liechtenstein and Jasmine, a model from son Sam's (Dan Evans) poster.
Jasmine and Desmon are shown to be polar behavioral opposites. Jasmine is friendly and intelligent. Via her telepathic abilities she quickly becomes Sam's girlfriend. Desmon on the other hand is ill-behaved, surly, and mischievously malevolent. His mischievous personality drives him to pull terrible tricks on Sam's family via his powers—for example, Lindy overuses the phone, so Desmon stuffs the receiver in her mouth, causing her to go to the ER to have it extracted. Handyman Floyd is hurt by some cut wires a vindictive Desmon moves with psychokinesis giving him a severe electric shock. Suffering difficulties in retaining his new body, Desmon frightens off the maid Emma when he tries to seduce her. Reverend Lawrence Newman, Nathan's college roommate, tries some bedroom antics with Nathan's sister, Angelica; Desmon, clinging to the ceiling above them, uses his powers to transform Lawrence's penis into a dragon-like creature that attacks him.

Nancy's cousin