Summarize the conversation between Roderigo and Iago in IV.II. 172-231 in Othello.

Roderigo has reached the end of his rope, again, and is
telling Iago that he must either have results for all his payment or that he is going to
quit the whole affair.  Once he threatens to tell Desdemona of all his doings and this
is a great threat to Iago's plans.

So Iago lays on the
praise nice and thick, tells Roderigo that now he sees the strength and passion in him
and he says that he believes that things will really work out this time.  Iago tells
Roderigo that he will be with Desdemona by the next night or Roderigo can torture him to
death.

Iago tells Roderigo that Cassio and Desdemona are
going to run off together.  So Iago sets him up to duel with Cassio, promising Roderigo
that he will be able to kill him, leaving Desdemona for
Roderigo.