Ophelia's songs seem like riddles and nonsense2, yet they are similar to the patterns of speech by Hamlet, revealing truths and true emotions, and at times sarcasm.
The Valentine Song cleans her soul, and perhaps she believed the brook would cleanse her body. He tells Ophelia he never loved her, calls her father a fishmonger, and in subtle ways calls his mother a whore and her new husband a murderer Ophelia's is set up for death from the first act of the play, in Ophelia's encounters with Polonius and Laertes.
Specifically, Hamlet and Ophelia, although they both appear to be mad at times, their downfall or supposed downfall is quite different.
Laertes brotherly advice is demanding.
The connection of one to the other, of character to condition, is so intertwined and entangled that Hamlet has come to symbolize the particular form of madness i.
Sometimes it is faked, sometimes it is nonsensical. Hamlet turns his madness on and off depending on the company he keeps