To understand Harold Pinter's plays, we must first understand the 'theater of the absurd.' This is because Pinter is one of the few playwrights connected to this absurdist movement in theater.
The word 'absurd' as defined by this movement, takes its context from the idea that life is largely meaningless. The absurdist movement questions why we live and why we die, but provides no answers for such a state of affairs. With the advent of the two world wars, absurdist philosophers further highlighted the hopelessness of life under the absurdity of Soviet-style Marxist rule.
On the one hand, proponents of Marxism heralded its doctrines as the potential answer to mankind's every problem; on the other hand, the tenets of Marxism brought about untold suffering and degradation to millions. None who lived under the system dared to question the validity of such an ideology. All were expected to acknowledge (even at the expense of their own sanity), the benefits of such a system. Any who dared to veer from this path were touted as subversives and traitors. Hence, the absurdity of the situation.
Many found, even as they suffered under totalitarian regimes, that their religious faith fell far short in according them the answers they desperately needed.
Theater of the absurd conventions.
Harold Pinter and the theater of the absurd.
Hence, absurdist theater is all about presenting snapshots of certain situations in an individual character's life. Absurdist plays do not debate morality or philosophies; the authorial voice is not lent to designing the kind of neat plot-lines theater goers have come to expect from traditional theater. No, the purpose of an absurdist play is to paint an unvarnished truth of the bewilderment and confusion human beings endure when their lives are deprived of the certainties which previously characterized their existence. So, when an individual is deprived of the comforts of a rational existence, what becomes of his ability to express himself and to extricate himself from such an irrational state of affairs?
It is no wonder that all three of the plays you mention are characterized by a disturbing lack of cohesion in terms of language and structure. We are disturbed that we can't make heads or tails out of Davies, Max, and Stanley's lives; however, Pinter is subtly trying to tell us that neither of these three men can either. The famous Pinter pregnant pause or silence is clearly utilized to symbolize utter detachment, confusion, and the volatility inherent in numerous conversations.
Language of silence in the plays of Harold Pinter.
In The Homecoming, Max is a cantankerous, old man. He hides his fear of irrelevance through an outwardly intimidating demeanor; his bravado and loud recriminations causes him to have a contentious relationship with his sons (Lenny, Joey, and Teddy). His rapport (if it can be called that) with his sons is characteristically dysfunctional. Max is as apt to be physically abusive as he is to be physically affectionate. After Max punches Joey in the stomach (because Joey apologized for Max's crude characterization of Ruth as a 'smelly scruffer' and a 'stinking pox-ridden slut.'), he is openly affectionate with Teddy.
Pinter portrays Max as a man who is afraid, both for the loss of his virility and for his fast eroding sexual relevance to any woman. He struggles to maintain his dominance in a household of men through intimidation and callous manipulation of everyone's emotions. The play ends with Max, crawling towards Ruth, begging for some semblance of feminine affection from the calculating woman.
In The Birthday Party, Stanley Webber must protect himself from some unknown, nebulous past. He lodges with Petey and Meg Boles in a seaside town. Stanley allows himself to indulge in a flirtation of sorts with his married landlady whenever Petey is not at home. However, we get the idea that he is also somewhat repulsed by Meg's sexually suggestive bantering and that he only participates to insulate himself from an honest assessment of his own precarious situation in life. Pinter never really tells us what Stanley fears, but both McCann and Goldberg soon introduce a sinister element into the story.
As the play continues, it becomes apparent to us that Stanley is afraid of the two men. He tries to get them to leave through equivocation and subterfuge, but is unsuccessful. In the end, both men's bizarre and disturbing interrogation techniques drive Stanley to mental oblivion; because of their verbal onslaught, Stanley suffers a nervous breakdown, his speech becomes characterized by unintelligible grunting, and he becomes a shadow of himself.
As with our initial meeting of Stanley, this is a man who evades trouble through denial and mental detachment. He is also emotionally weak and impressionable and is reduced to the level of an imbecile as a result of McCann's and Goldberg's machinations. He is no match, physically or mentally for both men, and one can only guess what his coming fate is at the hands of Monty's 'special treatment.'