I wanted to show the progression of Nexious and Rue from smeets to adulthood.
Smeets: When Rue and Nexious met, Rue was an anxious ball of nerves being picked on by the other smeets for being so small. Nexious was the only one to stand up for him. She took no nonsense and made sure Rue got his fair share of things from then on.
Teens: When they got their assignments Rue and Nex were placed together due to their compatibility. Rue had grown more comfortable, leading to his more silly nature coming out. Nexious only grew more stern, bordering on and later becoming cruelty as she got older.
Adults: After the crash Rue couldn't bring himself to joke around much anymore. In stark contrast, thanks to losing a decent chunk of her memories, Nexious loosened up and became the more lighthearted of the two.