Victor, the protagonist of Mary Shelley's Frankenstein, seems to be unable to deal with any traumatic events in his life. If anything traumatic befalls him, Victor lapses into sudden illnesses. For some, these illnesses may act as a defense mechanism which allows Victor to escape from the reality of things. For others, these sudden illnesses may be the "things" which force Victor to recognize exactly what he has done.
The first time readers see Victor fall ill is in chapter five. Victor has just found success in reanimating life. Horrified by the creature, Victor paces his loft until he falls into a fitful sleep. During this sleep, Victor dreams of Elizabeth and her death. Awaking from the dream, Victor finds himself in a cold sweat with his muscles convulsing. Later the next day, after Clerval arrives, Victor believes that he sees his monster. Immediately, Victor falls down in a "fit." It takes months for him to recover. This illness could illustrate Victor's inability to face what he has done.
Victor also becomes very ill when he arrives in Ireland. After being charged with Clerval's murder, Victor falls into illness again. During this illness, he rants and raves that he is responsible for the deaths of William, Justine, and Clerval. This illness could illustrate a time where Victor is able to understand (and come to terms with) his responsibility for creating the Creature.
Both of these times Victor falls ill, he takes many months to recover. For some, this may illustrate a defense which allows him to "ignore" what he has done. On the other hand, Victor may need this time to recover from the shock his body and mind has gone through. Regardless, Victor seems far too weak to really deal with life. He seems to push himself to the brink of exhaustion only to fall into illness when he has gone too far