Animal Theme Naming: Downplayed. When their family went to the zoo, Leo liked to see the lions because his name — Leo — evokes the animal.
Ascended Extra: That blonde girl Leo met in "Slash and Destroy" is Shadow's best friend Maddie, Casey having chaperoned for them regularly.
Because Destiny Says So: Much like when Mikey was mutated, Leo's mutation worries Miwa that all of her brothers becoming turtles is a bad omen written in the multiverse.
Big Brother Instinct: Pretty much everyone has a story where Leo was there for them.
When they were younger, Leo saved Mikey from an aggressive goat at a petting zoo, an experience that would have crippled him for life if he hadn't been there.
When Donatello was being bullied by an older kid in his class, Leo was the first to notice Donnie's shift in mood and ask him about it. The next day, the bully stopped bothering him, he and his friends having very visible black-eyes.
Before Donnie and April go on their first date, Leo stops by to give April the "if you hurt my sibling" talk standard for this sort of thing. He goes onto explain to April just how strong Donnie's feelings for her are, cementing their relationship.
When Casey had to leave to get bandages for his little sister who had broken her teacup, Leo offers to chaperone her and her friend. By the time Casey gets back, he is fully committed to their tea party without complaint, even enthralling them on what tea-parties are like in Japanese culture.
When they were little, Miwa and Leo were left behind at home to look after a sick Michelangelo while their parents took Donnie and Raph to martial arts camp, Miwa expected to stay and help for being the oldest while Leo volunteered. Angry that she couldn't go, she went to watch TV while Leo obeyed his parents and looked after Mikey. Later, Mikey's fever reaches levels so dangerous that they called an ambulance, Leo's diligence being what saved him. While Miwa is grateful for that, she is still ashamed of herself for it to this day.
Breather Episode: After such a high octane series of chapters involving the invasion of New York, Tang Shen's mutation, Leo nearly dying and his mutation, here the chapter falls more into a slice-of-life plot where the group regales little moments about how Leonardo was always there for them.
Call-Back: Raphael's story is basically what was going on with him, Donnie and Mikey during the events of "Nightmares and Bad Blood".
Child Prodigy: Unsurprisingly, Donatello skipped a grade when he was younger. Unfortunately, this left him an object of mockery for his classmates, Vernon and his friends mocking him for being a nerd.
