He killed Roderigo.
Iago has been systematically conning Roderigo out of his money, saying that he is using it to try to get Desdemona to dump Othello and go for Roderigo instead. Iago knows that Desdemona will never do this, and has been simply pocketing the money. Roderigo is starting to catch on, so Iago feeds him the same line about Cassio and Desdemona having an affair and sets Roderigo on to murder Cassio. His objective is to get rid of both of them. Roderigo does stab Cassio, who Iago takes for dead, so Iago kills Roderigo himself.
He thought Roderigo already had.
Iago does the plotting alone; Roderigo is his dupe and has no more idea how he is being used than Cassio does. In Act II Scene 3 Iago makes sure both are drunk and quarrelsome and then eggs Roderigo on so Cassio will fight with him, thus ensuring Cassio's dismissal. In Act IV Scene 2 Iago lies to Roderigo, telling him that Othello is being sent to Mauretania where Roderigo will never have a chance to see Desdemona. Iago tells him that this is only possible because there is a competent replacement for Othello on hand in Cyprus in the person of Cassio. Get rid of Cassio, and Othello must stay in Cyprus. In this way Iago dupes Roderigo into trying to murder Cassio in Act V.
Iago's plan is to make Cassio drunk and get him into a brawl that will ruin Cassio's reputation and cause him to lose his position. He urges Roderigo to provoke Cassio "to put our Cassio in some action/ that may offend the isle." As usual,Roderigo is duped by Iago's manipulative words and agrees to do this, even though all he ends up with is a sound beating from Cassio. Iago, however, succeeds in getting Cassio dismissed from his lieutenancy to Othello, which plays in toIago's master plan to ruin Othello.
He killed Roderigo.
Iago has been systematically conning Roderigo out of his money, saying that he is using it to try to get Desdemona to dump Othello and go for Roderigo instead. Iago knows that Desdemona will never do this, and has been simply pocketing the money. Roderigo is starting to catch on, so Iago feeds him the same line about Cassio and Desdemona having an affair and sets Roderigo on to murder Cassio. His objective is to get rid of both of them. Roderigo does stab Cassio, who Iago takes for dead, so Iago kills Roderigo himself.
He thought Roderigo already had.
Iago does the plotting alone; Roderigo is his dupe and has no more idea how he is being used than Cassio does. In Act II Scene 3 Iago makes sure both are drunk and quarrelsome and then eggs Roderigo on so Cassio will fight with him, thus ensuring Cassio's dismissal. In Act IV Scene 2 Iago lies to Roderigo, telling him that Othello is being sent to Mauretania where Roderigo will never have a chance to see Desdemona. Iago tells him that this is only possible because there is a competent replacement for Othello on hand in Cyprus in the person of Cassio. Get rid of Cassio, and Othello must stay in Cyprus. In this way Iago dupes Roderigo into trying to murder Cassio in Act V.
Iago's plan is to make Cassio drunk and get him into a brawl that will ruin Cassio's reputation and cause him to lose his position. He urges Roderigo to provoke Cassio "to put our Cassio in some action/ that may offend the isle." As usual,Roderigo is duped by Iago's manipulative words and agrees to do this, even though all he ends up with is a sound beating from Cassio. Iago, however, succeeds in getting Cassio dismissed from his lieutenancy to Othello, which plays in toIago's master plan to ruin Othello.
Roderigo was becoming aware of the fact that the huge sums of money he had given Iago to help seduce Desdemona had been going directly into Iago's retirement fund. When a conman cannot blow off the mark, either he runs or arranges for him to be killed. Actually Iago wanted Cassio to kill Roderigo but he didn't quite do the job so Iago has to finish it.
It would make it seem that Iago did his part in the plan, where Iago kills Cassio and Othello kills Desdemona. Even though Iago got Roderigo to do it for him.
Cassio
Roderigo attacked Cassio but did not kill him. Iago had intended that Roderigo would kill Cassio and then Iago would kill Roderigo. In the scenario you are suggesting, Roderigo is a much more successful fighter than we thought and manages to kill both Cassio and Iago. He would then no doubt have been charged with killing them and might offer in his defence how Iago had conned him out of all his money. Emilia would be able to tell her story and live and it would certainly corroborate what Roderigo would say. Unfortunately none of this would come in time to save Othello or Desdemona, who would both end up dead in any event. Since Cassio is dead, someone else would have to be governor of Cyprus.
Iago hated Cassio because he was promoted to lieutenant instead of Iago. This was his motive for getting him dismissed, for persuading Othello to hate him, and for trying to kill him. Iago was using Roderigo as a source of money, but Roderigo was beginning to realize that he was Iago's dupe, and was becoming dangerous to Iago--hence he had to be killed.
Iago wanted Cassio to drink more wine because he wanted Cassio to be drunk and argumentative when Roderigo would approach him later that night. Iago told Montano that Cassio was drunk every night. He wanted to cast doubt on Othello's judgment for appointing Cassio, by implying that Cassio may be drunk during battle. This led to Othello stripping Cassio of his position. Othello thought that Cassio was irresponsible and dishonourable.
He says that Othello placed Cassio as his lieutenant instead of him.