The gender spectrum
Gender seems in nature to be purely binary, and it might be an overstatement to say that no one experiences traditional gender, but there are certainly people who understand gender in different ways, including Sydney's conception of gender as a spectrum, one on which she fell mostly toward masculinity. This is a valuable part of his identity and it is something very meaningful and beautiful as well.
Diversity and homogeny
Sid and India lived in two fairly diverse places, Trinidad and Canada, but by the principles of diversity, that meant that there were always people who disapproved of two lesbian women raising a son. Nevertheless, Sydney's cool, inviting personality is a statement of the other side of diversity, the beautiful flourishing of unique identities. Ironically, you can't have the latter without the former.
Zain, the ironic anima
Perhaps it's just part of life as a man to experience rejection by women. Sydney learns this from her crush on Zain, an unrequited attraction. There is a balance between Sydney not getting to be with who she wants and Jonathan and India not getting to be with Sydney, though they love and miss the person he used to be with them.
Sideways and forward
The title of the book is ironic in nature, and it indicates the way Sydney moved forward in life by adjusting herself on the gender spectrum (moving sideways into a male identity). Their stories confirm this principle, and they agree that life is full of strange little riddles like this.
The irony of tropics and snow
Canada and Trinidad aren't very similar at all. One is cold and somewhat polite or severe, and the other one is an island in the tropics. The difference is one of temperament and environment, accentuating the novel's main idea, that things exist in a spectrum, and that perhaps people belong in certain places and don't belong in other places. Sydney wants Jonathan to understand that she did not feel like she belonged in that former life.
