The nightmare lasted for more than half of the night but could have gone longer, as Tianlong Yun could still keep going at it, but he couldn't overuse his toy at the moment.
He needed her help to escape this place, and he couldn't allow her to become suspicious of the people around her, otherwise, he might suffer another deadly attack.
With those thoughts in mind, he let the extremely tired Princess rest a bit, and be fresh for later, as he put her little brother to sleep, and sent him somewhere else.
He was his insurance for the Ruthless Princess's loyalty, so he had to make sure that he took good care of him.
At the moment he could be considered to have bought his ticket out of this place, and he just needed the plane to come and take him away.
Of course, his plans for the siblings wouldn't end with just his escape from the place, as they had something really valuable that he needed, their Royal Vampire bloodline, and highest levels of the divine skills.