Lethe's Arrogance
Lethe wants to marry Susan but knows that Thomasine does not like him. He cannot understand why this is and is far to arrogant to imagine that it might be because of his questionable character. He concludes that she must actually be in love with him herself, that's the only reasonable explanation. He writes her a letter telling her not to worry, that once he is married to her daughter they will be able to have an affair that is never discovered. She is furious and hates him even more. The irony of this is that he is so arrogant that he does not realize she despises him because of his arrogance.
Easy's Name
Easy is so-called by the playwright because he is an easy mark, an easy dupe, and very gullible. However, he emerges triumphant at the end of the play, having engineered an impressive scheme to secure his lands back again and to protect his marriage to Thomasine. This is ironic because it seems he is not such an easy mark after all.
Quomodo's Faked Death
Quomodo fakes his own death for both financial gain and also so that he can see how people react to it. He believes he will be able to reclaim Easy's lands whilst enjoying the mourning that goes on as people learn of his passing. The irony here is that he signs away the lands whilst in his disguise, and also that nobody is very unhappy at all that he has died; in fact, they are rather delighted, and nobody has a good word to say about him.
Lethe's Mother
Lethe cannot wait to leave Scotland, and particularly the poverty of his youth, behind. He does not want to see his family again. It is ironic that when his mother arrives in London (but does not recognize him) that he has to keep her extremely close to him to ensure that she does not discover his identity, or tell anyone that they are related.
Quomodo Telling The Truth
Quomodo is a natural conman and so it is not natural for him to tell the truth. When the judge asks him if he duped and swindled Easy out of his lands, he of course denies it, which the judge then uses as evidence that he is not the real Quomodo; the real Quomodo would know that he had done these things and would therefore be able to answer the question correctly. Quomodo then has to actually tell the truth in order to make the judge believe he is the real Quomodo, returned, which of course then prevents him from ousting Easy as Thomasine's husband, and from getting back the lands that he had swindled.
