Can you recommend some youth novels about teacher-student relationships or brother-sister relationships?

Time stopped at eighteen for Ji Yi, and now all she wants to do is pick up from where she left off. Her career depends on it, and on top of that, she has to survive a fake marriage turned real! Some missed opportunities are irreplaceable, and some misunderstandings between them have proven near-fatal, but for He Jichen, he isn’t just a pretty face—he’s an opportunist. They may have lost their prime years together, but He Jichen is more than willing to spend his remaining years with her. If only she would just trust him… Will Ji Yi be able to find true love in this life? Can she outmaneuver all the snakes plotting her downfall? Only time will tell...

Keeley, a simple plain Jane, hits the jackpot. [No, she did not win the lottery!] At least that's what she thinks when she marries the most eligible bachelor in New York City: Aaron, a wealthy cold-hearted heartthrob and Tycoon. She wants to show the world that she deserves her position and bends over backward to fit into his world. One beautiful day, Aaron hands her a document asking her to sign. A divorce paper... "She's pregnant, and I need to take responsibility." That is the last thing that keeps on playing in her mind before she takes her last breath. Keeley dies, a 'hit and run'. [End of story. Not!] For some unexplainable reason, she wakes up as her younger self. A young high school girl, around the time when she first meets her cheating husband. Remembering her life with Aaron before she died, she makes a promise to herself that she will do everything in her power to avoid him at all costs. Will she be able to keep her promise when Aaron has his own plans as well, specifically for her? Or will she repeat history and fall for him once more... Why not journey with me and find out the truth behind their story. *Cover art by polkadottedscrunchie*

.

The Pokemon World. One filled with mysteries, schemes, monsters, and even eldritch gods. But honestly? It's not as bad as it seems. Even a flat broke snot-nosed Youngster could succeed in a world like this. And our protagonist? He's determined to prove it. [Isekai, OC] *** A mixture of Games, Anime, Manga, and my own headcanon. In other words, it's an AU.

After transmigrating into a harem novel, Lin Xiao became the villainous Eldest Senior Brother of the Azure Mist Sect. By following the original storyline and being a pesky villain, he could eventually attain his reward of becoming immortal. Having no other choice, he carried out his duty as a villain conscientiously. He would tease Fourth Junior Sister, steal Third Junior Sister’s clothes and spike Second Junior Sister’s drink. Finally, the day when Ye Chen, the male protagonist, joined the sect came. Lin Xiao was exhilarated. According to the original plot, he would attempt to Ye Chen, be caught by his Junior Sisters, and be humiliated by Ye Chen. Yet, to Lin Xiao’s surprise… “Big Brother is too kind. The poison he has prepared is such a child's play. Let me show him how it’s done.” Second Junior Sister said. “Kill Ye Chen! Kidnap Eldest Senior Brother! He is mine!” Third Junior Sister declared. “Kill everyone! Let’s create a world with only Eldest Senior Brother in it!” Fourth Junior Sister exclaimed. “My sweet disciple, he’s so cute even when he tries to poison someone furtively.” His beautiful master swooned. Lin Xiao screamed internally, “Read the scripts, all of you! I’m the one who is supposed to be killed!”