In Act II, scene i, Reynaldo is asked to spy on Laertes in France. Polonius is concerned that his son is not acting like the "noble youth" he is and Reynaldo is tasked with acquiring information on how Laertes is conducting himself.
This event says a lot about Polonius and his character. First of all, he doesn't trust either of his children. In Act I, he leaves Laertes with specific fatherly, but intrusive, advice, after lecturing Ophelia about Hamlet's motives and desires. Secondly, this "ruse" makes him look petty and deceptive. While his trick is clever, as he himself notes, "Your bait of falsehood takes this carp of truth:/ And thus do we of wisdom and of reach/ With windlasses and with assays of bias/ By indirections find directions out," it illustrates his fatal flaw. This is only the first of many "tricks" and "ruses" that Polonius plans. In the end, he is the "victim of his own treachery."
The character of Polonius, in Shakespeare's Hamlet, proves himself to be a questionable parent at best when he asks "his man" Reynaldo to search out Laertes in France in order to examine Laertes' behavior. In other words, Polonius wants Reynaldo to be a devious spy. Laertes, of course, is Polonius' own son. Polonius has given Laertes quite a bit of (rambling) advice before Laertes goes to France to complete his studies. Obviously, Polonius doesn't trust his own offspring. Considering the expense of sending Reynaldo to France and verbally inquire about Laertes' whereabouts and doings, obviously Polonius finds this devious spying to be quite important. Let's look at some of the text in order to put Reynaldo as "spy" and Polonius as "questionable parent" under the literary microscope.
The guise as to which Reynaldo is to appear in France is to give Laertes "this money and these notes." In these first few lines of the chapter, some readers can be a bit confused because Polonius keeps using the pronoun "he" and never uses his son's actual name (Laertes). Still, Reynaldo is given strict instructions not to visit "him" (Laertes) until he is able to "make inquire of his behaviour."
Making this "inquire" is where the spying comes in. Next Polonius asks Reynaldo to be quite sure as to whom he is speaking in order to find the right people to ask about Laertes. He spends quite a few lines concentrating on this and asking Reynaldo to:
Inquire me first what Danskers are in Paris,
And how, and who, what means, and where they keep,
What company, at what expense; and finding
By this encompassment and drift of question
That they do know my son, come you more nearer
Than your particular demands will touch it.
Third, Polonius instructs Reynaldo not to reveal that he is actually spying but to say that he simply knows Laertes' "father and his friends, and in part him." Through it all Polonius continually asks Reynaldo if he is listening and marking the words that Polonius is saying. (I find this quite interesting because it shows that Polonius, himself, has the knowledge that he tends to ramble and, as a result, his listeners stop listening to him, ... quite often.)
Fourth, Polonius (amazingly) tells Reynaldo to tell whatever lies he pleases in order to falsely implicate Laertes in order to get the truth out of whoever is being spoken to. In fact, Polonius says:
Put on him
What forgeries you please—marry, none so rank
As may dishonour him, take heed of that—
But, sir, such wanton, wild and usual slips
As are companions noted and most known
To youth and liberty.
In other words, accuse Laertes of anything that makes "youth" both "common" and "wanton," although nothing that would "dishonour" Laertes. And when Reynaldo suggests "gaming," Polonius goes further and wants suggestions of more than that:
Ay, or drinking, fencing, swearing, quarrelling,
Drabbing. You may go so far.
Here, Reynaldo is surprised that Polonius would have his spy suggest such things because Reynaldo admits that "My lord, that would dishonour him." But Polonius dismisses Reynaldo's assumption because he wants Reynaldo to ask about those very particular things. According to Polonius, it all depends on the expert way that Reynaldo would "season" his words. Ironically, here Polonius does say that Reynaldo should not "put another scandal on him," but only such things as normal youth would do when away from home. Another irony here is that Reynaldo says nothing except the word "but," ... and Polonius then rambles how horrible Reynaldo is by even suggesting that Polonius is a bad father for suggesting this scam. In truth, Reynaldo says nothing of the sort.
Finally, Polonius tries to label what he is doing as a "trick of protection" because the final product (Polonius is sure) is that Laertes will be labeled as a "good sir" or a "friend" or a "gentleman." And after losing his place amid his rambling thoughts, Polonius asks Reynaldo what was being discussed and then blurts out that by using lies about Laertes,
Your bait of falsehood takes this carp of truth;
And thus do we of wisdom and of reach
In other words, Polonius thinks that lies will allow Reynaldo to learn the real truth of Laertes' doings. The reader should note the inconstancy and deviousness of this awkward request and, therefore, view Polonius as a questionable parent and, in fact, a questionable character from now on.
Polonius proves himself to be an untrusting parent by choosing to send Reynaldo to spy on Laertes even after speaking directly with his son already. After providing his son with a lengthy list of 'life rules' to follow while he is away at University.
These rules include:
"Give thy thoughts no tongue" - keep your thoughts to yourself
"Those friends thou hast, and their adoption tried, Grapple them unto thy soul with hoops of steel." - maintain the bonds of friendship
Polonius also goes on and on to Reynaldo with directions on how best to spy on his own son. Reynaldo's assignment to spy is far from noble, but it is as if Polonius can't help him self.