The irony of twin identity
It's hard enough to find one's identity alone, but as a twin, it's often difficult to make people pay attention to each person, as opposed to "the twins." In the end though, the irony deepens when they learn that as twins, they have more in common than they originally thought.
The irony of betrayal
When one person in a family betrays that same family, that's ironic, but when every person in the family betrays each other one, that's serious. The mother betrays the family with her affair. Noah betrays the family by hiding Jude's art. Jude betrays the family by throwing her brother's college application away.
The ironic death
When Dianna goes to be with her true love, her side lover, she dies horrifically. This death perplexes Dianna's twin children endlessly until finally, they all admit the guilt they feel about the death—but no one was 'guilty' of the crash, since it was a random accident. The timing was so ironic, the children each felt personally responsible.
The ironic drinking game
A game is supposed to be fun, but Noah finds himself driven nearly to suicide until his sister and friend stop him. This captures alcohol quite nicely as a drug. It often gives euphoria followed by a walloping dose of existential despair. Noah binge drinking was a sign not of his fun and health, but of his emotional instability.
Judy's poor timing
The characters in I'll Give You the Sun have a hard time parsing their responsibility out. When Dianna dies tragically, either twin immediately believes the narrative where they are each responsible for Dianna's random and tragic death. For Judy the problem is more abstract: She was having sex for the first time when her mother died in a car accident.
