The Grandmaster's daughter was named Vane Gast. How to put it? She wasn't a bad person, just a little foolish.
When Su Ming brought her up, he did not truly intend to tour any tower. He merely wanted to make things difficult for the Grandmaster. Everyone had a weakness, and this daughter was one of the Elder of the Universe's weaknesses.
The Grandmaster usually did not value this girl much. It was said that her mother had been a slave, but blood was still blood. Her status remained fairly high, and Sakaar's servants and guards still had to call her Young Miss when they saw her.
In the comics, she was an extreme xenophile who liked all kinds of aliens and often betrayed her father because of it.
It did not matter if one did not know the Grandmaster's weakness. As long as one had Vane Gast under control, a few foolish slogans like "all cosmic residents are family" and "everyone in the universe is equal" would be enough to persuade her. She would immediately place great trust in aliens like Deathstroke and spill every one of her father's weaknesses and the core of his plans, holding nothing back.
She was also blue-skinned and had inherited many of the Grandmaster's abilities: immortality, indestructibility, Cosmic Energy, and more. She could even directly open wormholes for the Space Teleportation of large forces. The only thing she had failed to inherit was his brain.
After testing each other during their meeting, Su Ming had deliberately pointed out her existence only to keep the Grandmaster from playing any tricks. At least for now, Deathstroke had no interest in playing any sort of game with him.
Sure enough, the rest of the afternoon passed peacefully. The three of them watched holographic programs in a luxurious