In Shelley's novel Frankenstein, what are Victor’s weaknesses? Give examples to support your answer.

Although he is a brilliant scientist from a wealthy family and is much loved, Victor's basic orientation is selfish.  He is egotistical and overly concerned with how he appears to the world - he first decides to push the limits of the unknown because he wants to leave his mark on the scientific world, and refuses to testify for Justine because he fears what the townspeople will think of him.  He is also single-minded to a fault.  During the time he was creating the monster at Ingolstadt, he completely isolates himself from family and friends, effectively cutting himself off from any sources of interaction and input that might have helped advise and temper his decisions to challenge the limits of "accepted" science.  Also, in his quest to capture the creature in the Arctic, he relentlessly pushes Walton's crew - who are already going out of their way for him - calling them cowards when they want to abandon the chase and return home. 

Victor's refusal to accept responsibility for his creation also stems from his basic self-centered nature.  The creature repulses him, and to acknowledge him before the world will make him look bad, so for the most part he just hopes it will go away.