What does the introduction and death of Ophelia add to the plot of Hamlet?
Poor Ophelia! She is played first by her father and brother and then later by Hamlet, her paramour.
Her trouble is youth. . . and the ignorance and passion) that comes with it. She is warned early by her brother that Hamlet is a Prince and could cause her trouble. Later, her father uses her to spy on Hamlet for his (the father's) personal gain. Young girls, at least shakespeare indicates, are easily "man"-ipulated!
Hamlet is on to her, so to speak, and he tells her to "go to hell" and that he loves her no longer. Later though, he snuggles with her, and makes crude jokes at her, during the viewing of a play. She is confused.
Hamlet later kills her father, which, in her brother's absence, proverbally, and somewhat literally, "sends her off the deep end" chanting sad songs and eventually drowning herself.
The two men in her life, her brother, and her would be husband, then both hop into her grave to having a "peeing match" as to which loves her and mourns her more.
Effectively, her death is the catalyst for the final scene in which these two duel (they are only supposed to be "playing") in which dublicity reigns and tragedy ensues.
A great play! Enjoy it.
By the way, her plight engendered a popular book on the troubles girls' struggle with in society. It's called "Reviving Ophelia"--you'ld have to look up the author but it's quite good for those interesting in the inner-workings of young women and their world.
Singer/Songwriter Natalie Merchant also has an album and title track by her name. Also good stuff!