What similarities are revealed between the characters in "The Interlopers"?

This is a great question. Ulrich von Gradwitz and Georg Znaeym share many similarities. Let me list four points.

First, they both inherit hatred from their grandfathers.  So, in this sense, they let the past cloud the present. We can also say that they allow hatred to blind commonsense.  The text actually states that they had “hate in their hearts.”  This hatred is so real that they wanted to kill each other.

Second, even though both men hate each other, when they finally meet eye to eye by chance in the woods, they hesitate to take their hatred to the next step, murder.  The implication is that they are not as bad as they could be. They both have a conscience.

Third, when the storm pins them down under a tree, they come to their senses in time. Ulrich is the first to bend.  He seeks reconciliation.  Georg refuses at first, but then he comes around.  Afterwards, they seek to be kind to one another. From this perspective, they both experience change.

Finally and unfortunately they also share the same fate.  They die.

Who is the static character in "The Interlopers"?

Since the characters of Ulrich von Gradwitz and Georg Znaeym, who begin the narrative of "The Interlopers" as mortal enemies apparently resolve their differences as they lie pinioned beneath the fallen mass of the beech tree, they must, then, be classified as dynamic characters. So, the reader is compelled to look beyond actual persons as the character who is flat/static. For, character can be defined, along with a person, as animals, things, or natural forces appearing in a literary work.

Clearly, Nature acts as the antagonist to von Gradwitz and Znaeym when their actions are foiled by the violence of the storm that "overwhelmed them both" and their intentions of shooting one another are quickly ended by the mass of falling beech tree limbs upon them. Nevertheless, it would seem that this accident of Nature has positive results as the two adversaries resolve their enmity, and, thus, Nature has changed to an emissary of friendship.  But, this is not so.  Nature remains the adversary as it attacks again in the form of wolves who answer the men's cries.  Therefore, in Saki's short story, it is Nature that is the flat/static character.

Compare the two characters in the story "The Interlopers." How do they share similar experiences in the story?

Both Ulrich and Georg have grown up under the cloud of this hatred. They were both raised in the shadow of this long lasting feud. They both want nothing more than to see the other dead. They play perfect character parallels in this story because of their similarities. This is done very well to make his point as they feel such hatred for each other. The are both the heads of their respected families and both feel that they are completely justified in laying claim to this disputed piece of territory that borders their land. They end up trapped together under a tree and ending the feud. They decide that the will put away all the hate and be friends. Through this, they have both gone on the same emotional journey through this story; they moved from pure hatred to friendship.

Who is the protagonist in "The Interlopers" by Saki?

This is a great question, as the story does not have a clear protagonist or antagonist. Part of the reason for this is, because both men, Ulrich von Gradwitz and Georg Znaeym, are so similar. We can see this in three ways.

First, they both inherit hatred from their grandfathers. So, in this sense, they let the past cloud the present.  We can also say that they allow hatred to blind commonsense. Second, even though both men hate each other, when they finally meet each other eye to eye by chance in the woods, they hesitate from carrying out their hatred. To put it another way, they don’t immediately kill each other.  This shows that they are not purely evil.  There have second thoughts about their enmity. Finally, when the storm pins them down under a tree, they come to their senses.

However, if we had to choose on protagonist, the first act of kindness is demonstrated by Ulrich.  He pities his enemy. As he gets one hand free, he tosses wine to Georg. This might make him the protagonist but barely so. Here is the quote.

“Could you reach this flask if I threw it over to you?” asked Ulrich suddenly. “There is good wine in it, and one may as well be as comfortable as one can. Let us drink, even if tonight one of us dies.”

“No, I can scarcely see anything; there is so much blood caked round my eyes,” said Georg; “and in any case I don’t drink wine with an enemy.”

Describe the characters in "The Interlopers."

Ulrich comes from a line of wealthy landowners. As his ancestors did, he guards his land zealously and has a particular animosity towards Georg Znaeym. Georg comes from a line of small landowners. Like his ancestors, he still poaches on Ulrich's land even thought a lawsuit had been settled, giving the land to Ulrich and his family. Ulrich's and Georg's families have been feuding over this land for three generations. So, we can say that both men are stubborn in upholding this tradition of fighting over land. 

Note that the land is not valuable in terms of hunting. " . . . the narrow strip of precipitous woodland that lay on its outskirt was not remarkable for the game it harbored or the shooting it afforded . . ." This highlights how pointless the feud continues to be. The men are trapped by their stubbornness and perhaps by a twisted sense of loyalty to their predecessors who feuded as well. 

As fate has it, the two men are poised to kill each other, but they hesitate: 

But a man who has been brought up under the code of a restraining civilization cannot easily nerve himself to shoot down his neighbor in cold blood and without a word spoken, except for an offense against his hearth and honor. 

This hesitation suggests a slight remnant of reason in both men. When they become trapped under the tree, they still swear to kill one another. But after assessing the situation and perhaps considering his own mortality, Ulrich offers Georg a drink. This is the first friendly gesture that has occurred between these two men. Georg refuses at first. But when Ulrich promises to set him free if his (Ulrich's) men arrive first, Georg finally returns the gesture and the men become friends.

They begin as sworn enemies, too stubborn to break from the tradition of the feud. But in a situation in which they both contemplate dying (together), they are able to overcome their feud. They needed to be forced into a predicament like this in which they could either bond or continue to be enemies. 

Who is the main character in "The Interlopers"?

In my opinion, this is a trick question because there are truly two main characters in "The Interlopers."  If I were forced to choose one, I would choose Ulrich von Gradwitz; however, Georg Znaeym has been Ulrich's enemy from birth and is just as important to the story.  The entire story is about their exploits together as grown men.  Ulrich von Gradwitz is a wealthy landowner.  He owns a very important stretch of forest land, but he knows that Georg continues to hunt on this land on purpose:  Georg is protesting Ulrich's right to own the land.  When the story takes place, Ulrich organizes a group to find Georg, so Georg can be killed.  Ironically, both men end up getting trapped under a tree because of a lightning strike, and it is Ulrich that offers to make amends by sharing a drink with Georg.  The other main character, Georg Znaeym, instead of being a wealthy landowner is a small landowner.  Georg has always been unhappy about Ulrich getting the rights to the disputed piece of forest land, and as a result calls it a ‘‘stolen forest.'' He does end up making amends with Ulrich under the tree.

Who is the antagonist in "The Interlopers"?

The antagonist of a story is the character who is in conflict with the protagonist, and the protagonist is the main character in the story. The main character in "The Interlopers" is often seen as Ulrich von Gradwitz. He is the character we meet first, and he is the character through whose perspective we read the story.

At the beginning of the story, we are told that there is a long-running feud between Ulrich and a man named Georg Znaeym. We are told that "if there was a man whom [Ulrich] detested and wished ill to it was Georg Znaeym." Ulrich hates Georg because he thinks that Georg is a "game-snatcher" and because Georg challenges Ulrich's ownership of and entitlement to a "narrow strip of precipitous woodland." It is the contested ownership of this strip of land which is the cause of the antagonism between the two men.

We are also told that both men, since they were boys, have "thirsted for one another's blood" and "prayed that misfortune might fall on the other." Ulrich hates Georg so much that he seems prepared to kill him. Indeed, Ulrich hopes that he might come across Georg in the woods, "with none to witness." The implication here is certainly that Ulrich is thinking of murder.

When the two enemies do come face-to-face, they each point their rifle at the other, each with "hate in his heart and murder uppermost in his mind." However, by the end of the story, the two men reconcile and look forward to a future where they can live peaceably as neighbors. Thus, by the end of the story, Georg is no longer the antagonist.

However, it is also important to note that nature can also be seen as the antagonist of "The Interlopers," as once both Ulrich and Georg come to a level of understanding, they are presumably not rescued by their men and are instead devoured by a pack of wolves, who, much like the land itself, are indifferent to the two men's petty, generations-long quarrel. Conversely, Georg and Ulrich can also be seen as the antagonists of the story, whose pride and arrogance at the notion of the land ever truly belonging to them ultimately bring about their downfall.