In Act I of "Julius Caesar," what are the moods and loyalties of the Roman mob compared to other groups of people?

At the opening of Julius Caesar, the crowds are cheering Caesar's triumphant return to Rome after the defeat of Pompey.  Marullus and Flavius are reprimanding the crowd for their cheers because, not long ago, they were cheering just as loudly for Pompey when HE passed in the streets.  This illustrates how fickle the people are and how they are able to quickly change loyalties to whoever is in power.  Marullus and Flavius are tearing down the decorations that adorn the statues of Caesar because they are not afraid to speak out.  The general population, however, seems to welcome each new leader with open arms (and a holiday off from working...).  Mark Antony understands this fact about the people and uses it to his advantage when Caesar is later assassinated by the conspirators.  The first to speak to the crowd after the death of Caesar is Brutus, and he manages to convince them that Caesar was too ambitious and would have ruined Rome.  They begin to chant that they want Brutus to be the new ruler (forgetting all about how they'd recently been singing Caesar's praises)... until Antony speaks.  Within minutes, Antony manages to turn the crowds against Brutus, Cassius, and the other conspirators, once again demonstrating the fickleness of the crowd.  The scene at the beginning of Act I with Marullus and Flavius' reprimands foreshadow the events of Act III.