How would one construct a thesis answering the questions, how are the servants Maria and Malvolio treated differently by the other characters around them, such as Sir Toby, Sir Andrew, and Fabian, and why are they treated differently as seen in Shakespeare's Twelfth Night?
While it will be useful to look at the differences between how Sirs Toby and Andrew, and Fabian treat Maria vs. how they treat Malvolio, we must also remember that the first four mentioned names are so similar in mindset that they have formed a sort of clique headed by Maria, so naturally they would treat each other differently from Malvolio. Another more important relationship to look at would be the difference between how Olivia treats Malvolio vs. how she treats members of the clique, especially Maria. It's also important to remember that Shakespeare wrote Twelfth Night to celebrate the Feast of Epiphany, a holiday recognized on the twelfth day/night after Christmas, and known to be quite wild and bawdy. Hence, Maria and her clique represent the wild, bawdy behavior characteristic of the holiday, while Malvolio represents more dignified, even puritanical behavior, leading to differences between Malvolio and Maria's clique.
As is pointed out by Maria, not only is Malvolio a Puritan, meaning an excessively virtuous and overly strict person, he is also a flatterer. She even objects to the fact that he is so dignified. We especially see all of her objections to Malvolio's behavior and characteristics in her lines:
The devil a Puritan that he is, or anything constantly, but a time-pleaser [flatterer]; an affectioned ass that cons state [appears dignified] without book and utters it by great swarths. (II.iii.135-38)
Essentially, Maria and her clique see Malvolio behaving as if he is above them. What's more, we also see that he possesses a great deal of arrogance. He is arrogant enough to insult Feste's skill as a fool, and he is arrogant enough to picture himself being married to Olivia when rising above one's station in this period of time was absolutely unheard of. Hence, Malvolio is different from Maria and her clique in that he is arrogant, self-righteous, puritanical, a flatterer, and highly dignified, wile Maria and her clique are wild and Bawdy.
It's these differences that also lead to different ways the characters are treated. Malvolio insults Maria and her clique, while Maria and the other characters play a cruel prank on Malvolio. However, ironically, it's Malvolio who Olivia treats with more respect rather than Maria or any member of her clique and even asks Malvolio his opinion. We especially see her consult Malvolio for his opinion in Act 1, Scene 5 when, angry with Feste for his long absence and trying to decide if she should forgive him, she turns to Malvolio and asks, "What think you of this fool, Malvolio? Doth he not mend?," which gives Malvolio his chance to insult Feste (I.v.66-67). The very fact that Olivia turns to Malvolio for advice shows us that she has more respect for Malvolio than Maria and her clique due to Malvolio's dignity, at least up until the moment he begins acting insane due to Maria and her clique's influence.
Hence, if we were to write a thesis putting all of these points together, we could assert:
- Malvolio represents dignified though arrogant behavior, while Maria and the others represent wild, bawdy behavior, leading to conflict between the characters as well as different ways in which characters treat them.
For your argument, you could point out that Olivia treats Malvolio with more respect; that Maria and her clique are all social friends; and that, due to Malvolio's virtue and arrogance, Maria and her click play a cruel joke on Malvolio.