Describe how the scenes between Antonio and Delio demonstrate the plays inevitable tragic conclusion

Antonio and Delio are steward's in the Malfi household who despite their low status play a very large role in the way the play progresses. From our first meeting with them we discern that they are basically decent men who are involved with the higher end of the society spectrum. Their many interludes serve to divulge information to the audience about their progress and the progress of the play.
Antonio and Delio operate as a team throughout most of the play even when they are geographically apart. Delio is Antonio's friend who acts as counselor to a counselor. His relationship is a mirror image of Cariola's with the Duchess. They are both advisors the distinctive thing separating them is that Delio is more intelligent than Antonio but Cariola less than the Duchess.
We can believe the character of Delio as he is given a humanizing element: a weakness. Delio attempts to seduce Julia into becoming his mistress but she skillfully fends him off saying " I'll go ask my husband ...