How does Nick Bottom serve the comedic purpose in A Midsummer Night's Dream?

Nick Bottom, a lower class weaver, provides comic relief in this play, and acts a foil or opposite to the high-born characters.

First, Bottom is comic in his role of actor. He and his fellow mechanicals, or working class friends, are rehearsing the play "Pyramus and Thisbe" in the sincere hope that it might be chosen to be performed at Theseus's wedding feast. Despite his enthusiasm, however, Bottom's bumbling ineptitude about all things dramatic create laughs. For example, he mispronounces words, such as when he says "Ercles" for Hercules and mistakes himself as a person whose chief talent is "for a tyrant," when it is anything but that. In fact, part of the comedy arises because of Bottom's lack of tyrannous cruelty. He is, in reality, overly concerned that the play will prove too frightening for the audience, saying in act III, scene 1 that they should write a prologue to reassure viewers that he will really not be killed, that the swords are not dangerous, and that he is Bottom, not Pyramus:

Let the prologue seem to say we will do
No harm with our swords, and that Pyramus is not
Killed indeed. And for the more better assurance, tell
Them that I, Pyramus, am not Pyramus, but Bottom the
Weaver. This will put them out of fear.

This is comic because it shows how literally Bottom takes theater: audiences, in contrast, know that what they are watching is not literally true.

This comic ineptitude will continue in act 5 as the play is performed and Bottom breaks character to communicate with the audience, responding to Theseus, who says when he curses the wall that the wall should curse back:

No, in truth, sir, he should not. “Deceiving me” is Thisbe’s cue. She is to enter now and I am to spy her through the wall. You shall see, it will fall pat as I told you. Yonder she comes.

Fortunately, the atmosphere is so festive at this point that nobody is bothered—and, in fact, Theseus is egging on the literalistic Bottom.

Another way Bottom adds to the comic elements of the play is to be given an ass's head by Puck. Puck does this as a prank, to show he thinks Bottom is an ass. However, this makes it all the funnier when Titania, the fairy queen, falls in love with him due to Oberon's love potion. Titania fawning over Bottom in his altered state shows that love truly is blind, and a form of lunacy, an important theme of the play.

However, Bottom never loses his pragmatism and knows he is not the beautiful being Titania thinks. This allows him to say some wise words about love to the queen:

To say the truth, reason and love keep
Little company together nowadays.

What aspects of Nick Bottom's behavior and personality in A Midsummer Night's Dream are comedic?

While other characters in A Midsummer Night's Dream are comic in more subtle ways (like Puck), Nick Bottom is a very overtly comic character. The humor comes from the way his beliefs about himself contrast so strongly with reality—in ways that are very obvious to the other characters and to the audience.

He believes himself to be an incredible actor who would be perfect in any part of the production of Pyramus and Thisbe, but his speeches are melodramatic and contain many rhetorical and grammatical mistakes; it is obvious to everyone else that he is a very poor actor whose peers are not pleased with him. He believes it is absolutely possible that the fairy queen Titania could fall in love with him, when it is clear to everyone else that he is not deserving of this. This contrast is made physical and even more obvious to the audience when his head is turned into that of an ass, and he has no idea.

The irony of the contrast between Bottom's beliefs and his reality is comedic, and it also allows for the audience to be "in on the joke."

What actions does Nick Bottom take in Shakespeare's A Midsummer Night's Dream?

Nick Bottom is an important character because all throughout the play he unifies fantasy with reality, thereby uniting two of Shakespeare's major themes in the play and proving Shakespeare's point that there really is not a significant difference between fantasy and reality.

We first see Bottom unify fantasy and reality by first being the one who holds the mechanicals' play within the play together. Bottom is chosen as Pyramus, the lead character, because he is apparently the best looking of the group, has the best manners, and has the best voice. We learn about Bottom's looks and manners in Quince's lines:

You can play no part but Pyramus; for Pyramus is a sweet-faced man; a proper man, as one shall see in a summer's day; a lovely gentleman-like man. (I.ii.77-79)

We also learn later that Bottom speaks well, or pronounces well, when Quince mourns Bottom's absence, saying that they cannot possibly perform the play without him as Bottom is the very model of a "sweet voice," or well spoken performer, which is what Quince is trying to say when he says, "[H]e is a very paramour for a sweet voice" (IV.ii.11-12). The mechanicals' play represents a break from the illusion of reality that Shakespeare's own play creates. In that sense, the mechanicals' play represents fantasy within reality. Since Bottom is the character that holds the play within the play together and ensures its enactment, he unites fantasy, which is the mechanicals' play, with reality, which is the reality of the Athenian civilization inside Shakespeare's own play.

Another way in which we see Bottom unite fantasy with reality is that he is the only character who unites the fairy world with the human world. While the fairies interact with the human world, such as Oberon and Puck manipulating Lysander and Demetrius into falling in love with whom they should be mated with and blessing all the lovers in Theseus's house, the fairies ultimately remain separate from the human world. In fact the fairies and humans are so separated that the humans wake up disoriented, half believing what they experienced was real and half believing it was a dream. While Bottom wakes up with the same amount of disorientation, Bottom is the only character who directly interacts with the fairy world. He directly interacts with the fairy world by becoming Titania's lover and being waited on hand and foot by fairies. It is through this interaction that Bottom also serves to unite the world of fantasy with the world of reality in the play.

Hence, we see that what Bottom does throughout the play is unite two of Shakespeare's major themes, fantasy and reality, showing us that the dividing line between the two is actually very thin. Bottom serves to prove Shakespeare's point that there really is not a very significant difference between what one perceives is an illusion and what is actually real.