Twelfth Night

The first act in Twelfth Night, like all Shakespeare plays, is the introduction of the characters. Specifically in Twelfth Night, I think how Olivia and Viola are portrayed and introduced is very interesting. The fact that they have both lost their brothers is what is comparable between the two. How each mourn for their brother is the part that is very interesting.
For example Olivia follows the traditional mourning style. She is in all black and has her face covered. Olivia's mourning is in contrast to that of Viola. She, instead, decides to take on the persona of her brother. She does not adopt his name but instead dresses like him and tries to embody his personality. The differences in how they mourn their brother can be related to the relation they have with their brother. As far as the text says Olivia has just lost a brother whereas Viola has lost her twin. The other part of her, in the sense that twins have a different connection than other siblings.
Also the relationship that Orsino has with both Olivia and Viola is very interesting because they are both very different and yet very much the same. He has an overzealous or an irrational view of a love for Olivia. She does not reciprocate his love and yet he still pursues her with the same urgency. Like whys this is seen in Viola in the fact that she loves Orsino and yet at this present time he will not reciprocate her love because she is a man in his eyes. It is a very interesting juxtaposition that is set up at the very beginning of the play and one that will last throughout the play until the end.
Twelfth Night has many different areas that are comparable and connected. There is a lot that happens that connects Olivia with Viola and how they are somewhat parallel throughout the entire play and so their comedic aspects are together along with their later love relationships.  
It will also be interesting to see how connected Sir Toby, Maria, and Feste are in the rest of the play. They were already set up in the first act and seem to be very prominent for the rest of the play.