As the lanky man overheard this, he came to a stop and his eyes flashed looking at the girl. Although the current immortals didn't have powers, this lanky man has dedicated his whole life to studying immortals power and he could say with confidence that, contrary to immortals beliefs, powers weren't manifested randomly. In cases like the council families, it was almost set in stone that their powers would be passed down from generation to generation.
In other words, it was always the same power, however, there existed some exceptions. What the lanky man found out about powers was that there was subconscious foundation for one's power. For normal immortals who weren't part of the families, the type of power that formed inside of them depended on one's desire. It was this desire that determined an immortal's abilities.
Although it wasn't always the exact powers they desired, it was always something similar to it or at least something in that direction.