Character Analysis
Jack is the most earnest character in a play about the value of earnestness — which makes him the primary comic target. He genuinely wants to be respectable; he genuinely loves Gwendolen; he genuinely feels guilty about Ernest. His mistake is believing that sincerity and performance are opposites, when the play shows they are the same thing. His revelation that he was always named Ernest resolves the plot while resolving nothing about his character.
How They Speak
More earnest, more straightforward than Algernon — he makes declarations rather than paradoxes. His language is solid where Algernon's is mercurial.