The phrase 'Mad blood' is personification, giving the blood human characteristics, and then coupled with 'Stirring' gives the idea that the heat is interfering with the characters' usual behaviour.
While Benvolio then tries to persuade Mercutio to retire from public view, he argues “The day is hot, the Capels are abroad, and, if we meet, we shall not 'scape a brawl,” This shows Benvolio's weariness for a meeting with the Capulets, while in contrast Mercutio is eager for a confrontation with them, as he believes causing a fight would mean the Capulets' death.
During Act 3, Scene 1 Shakespeare creates a fast paced, tense atmosphere, which aids the build up to events. He does this by using short sentence structures, and deliberate decisions made by the characters. This makes the audience become more involved with the play, as it makes them question the characters' morals and decisions and what they should have done instead.
Besides being tense and nail-bitingly brilliant, Act 3 Scene 1 is an energetic and vigorous scene, as there are many things happening at once. This excites the audience, and also adds to the shock when an event occurs. The stage directions are also a huge factor in Act 3 Scene 1, because of it's fast-paced and action-packed style, the audience need to understand every aspect of what's going on, or they would become bemused in all the entrancing/exiting, this is due to the fact that in the 16/17th century, plays were performed on a round stage surrounded by stalls and chairs, known as an 'Elizabethan Theatre'. People needed to do know what was going on at all times, thus Stage Directions were needed.
Upon the arrival of the Capulets, Mercutio deliberately misunderstands Tybalt when he asks if he is associated with Romeo, he mistook “Consort'st” for “Consort”. Mercutio immediately takes this as an insult, and replies “Here's my fiddlestick; here's that shall make you dance”. From this, we can see that Mercutio is already challenging Tybalt to a duel, as he is threatening Tybalt, hoping he would make the first move.
Another interpretation is that Mercutio's personality is naturally boisterous and irascible. Added to his natural hatred for the Capulets, causing him to purposely misunderstand Tybalt, in hope that it would cause a fighting situation.
Romeo howls “O, I am Fortune's fool!” after killing Tybalt, Juliet's cousin. He says this specifically because he was forced to kill his wife's cousin, taking revenge because of Mercutio's death. He is blaming fortune for these two deaths which have occurred in the scene, rather than to think about what he could have done to stop them occurring. Elizabethan audiences believed that a man too much in love becomes less manly, and effeminate. Romeo understands this belief, but indefinitely gives in to its label; He even states on line 114 “O Juliet! Thy beauty hath made me effeminate!”, although this is proven wrong after the death of Mercutio, as Romeo kills Tybalt as revenge. At this event, Romeo can be seen as the opposite of 'effeminate', and seems to forget who Tybalt actually is, only that he has killed Romeo's best friend.
The way in which the play is written makes the audience more sympathetic towards Romeo, because they know that he has just married Juliet, whilst the characters on stage do not.
After this event, the Prince arrives, and suddenly anger, hatred, and woe causes an alternate mood to arise, the murder of Tybalt is now the focus of the play and angry citizens telling the Prince to 'do his job' sets a different opinion of Romeo.
Lady Capulet is the main character to tell the Prince, “For blood of ours, shed blood of Montague.” this rephrases to “They killed a Capulet, so a Montague should be killed.”. Lady Capulet states this rash fact due to her strong hatred for Montagues, which is now peaking due to the death of her son. She does not care in what circumstances it occurred, only that a Montague is to blame.
The Prince then steps in to take responsibility, and thus banishes Romeo from Verona, ruining the constant companionship between Romeo and Juliet.
Shakespeare’s use of tension is a cornerstone of 'Romeo and Juliet'. It creates different atmospheres, which made the scene more exciting for the audience. His use of pathetic fallacy and stage directions are also very important, because in Elizabethan theatres they would not have been able to use lighting effects to create the weather and feeling, so they had to have a narration throughout the play.
So in conclusion I think that the most significant way Shakespeare created tension was by the weather, because it changed the atmosphere of the scene and also the mood of each character, which in turn caused drastic events to occur.