There was this beautiful MV on bilibili link here that had a scene where Sun Quan and Lv Meng went out by themselves on horses to hunt tigers. And then they got caught by Zhang Zhao when they came back.
Sun Quan was all smiles trying to pass it off as nothing, but Zhang Zhao was having none of it. And Lv Meng stood silently at the side trying to blend into the background. I can just imagine Zhang Zhao sighing "Ziming when I entrusted our lord's safety with you I meant stopping him, not protecting him while going along with it..."
If there is one incident I would point out as the most incongruent to Lv Meng's life story, it would be the fact that it was Zhang Zhao who recommended Lv Meng to take over when Deng Dang (his brother-in-law) died.
Zhang Zhao, who is famous for being stern and strict on propriety, who did not look favourably on ruffians and warriors, who made his disdain for someone as learned as Lu Su obvious. Yet somehow, he saw something in Lv Meng which made him look kindly upon the boy.
My personal headcannon is that Zhang Zhao's stuck-in-the-mud ways made it very difficult for him to find someone willing to listen to him preach. Even Sun Ce often used to act busy to get out of listening to Zhang Zhao's lectures.
Lv Meng, being the smart Alec he is, knows that Sun Ce views Zhang Zhao with high esteem. So in a bid to curry favour, he goes to Zhang Zhao with a sob story of being forced to fight despite his young age and how he never had the opportunity to go to school.
Zhang Zhao is overcome with sympathy for this poor young boy and takes him under his wing, teaching him about anything and everything (which Lv Meng manfully tries to pretend he finds interesting). Due to his close relationship with Zhang Zhao, Lv Meng gets to skip on menial labours ('he is coming with me for his lessons'), is given extra rations ('you must eat more as a growing boy') and all sorts of other small favours.
When Deng Dang passes away, plenty of other officers fight to gain control of his troops. But Zhang Zhao goes straight to Sun Ce, declaring that it is only proper that Lv Meng takes over from Deng Dang, and threatens to go into a long speech to explain exactly why. Sun Ce defers to Zhang Zhao's wisdom, and Lv Meng finally gets his own troops to command.
Years pass. Although Lv Meng has grown from footsoldier into Grand Commander, Zhang Zhao still sees him as that little boy who came to him for stories about morals and ethics. He calls Lv Meng to join him for dinner often, and though the latter is often too busy to make it, every once in a while they do manage a meal or two.
"Ziming" Zhang Zhao calls him, one of the few people who do. Perhaps it was even Zhang Zhao himself who originally gave Lv Meng that style name, since Lv Meng's father had passed on long before the chance came. He would nag for Lv Meng to take better care of himself, share knowledge from the latest books he had come across, and ask Lv Meng for anecdotes from his travels across the country. And Lv Meng would humour him, not only because Zhang Zhao remains an important advisor to Sun Quan, but also because over the course of 20+ years he had come to view this elderly man as a father figure of sorts.
At the end of the meal, Zhang Zhao would once again entrust the safety of his Lord Sun Quan into Lv Meng's hands. He knew that this young boy, whom he had watched grow up, would be up for the task.