In the play All My Sons, even though Larry is not seen throughout the play, how does he affect the many characters in the book?

In All My Sons by Arthur Miller, Larry is not seen throughout the play, yet he is a major influence on several characters in the play.  Chris says that Larry has been a road block for the family and that he and his parents have not been able to move on with their lives because they cannot deal with the loss of Larry:  "We're like at a railroad station waiting for a train that never comes in."  Kate refuses to accept the likelihood that Larry has been killed in the war, and she goes so far as to get their neighbor Frank to look up Larry's astrological chart to prove that his supposed day of death was actually his favored day.  Kate cannot accept Chris's proposal to marry Ann because she's "Larry's girl." 

Chris, on the other hand, claims that he has forgotten his brother, yet he does not openly propose his plans to marry Ann.  He says that he does not want to hurt his parents, yet he seems to regard his brother's memory as a barrier in his own life.  Although he has had feelings for Ann for years, he has waited to approach her which suggests that he may feel the sliver of possibility that either his brother is alive or that Ann has not accepted his death.

Ann has known all along that Larry killed himself in the war, but she did not immediately move on to a new relationship.  She says that she has been thinking about Chris, but she has never revealed these feelings to anyone.  She is also aware that Chris's mother does not want her in the house, but Ann does not stand up to Kate and therefore allows Larry's memory to continue to cause tension in the family.

Finally, Larry's letter is the catalyst which prompts Joe's suicide at the end of the play.  The reader is left to consider whether or not Joe has killed himself as a way of making amends with Larry and "all his sons" of the war, as a way of escaping his guilt, or as a way to avoid going to jail and dealing with his fatal decision; however, it remains that Larry's words and memory have prompted this action.

So, Larry's memory (and his words via his letter at the end of the play) greatly affect the characters in the play.