After the first four, no one else became a First Level member. They were all Second Level, which is also incredible.
The purity of the blood determines the level of a member after transformation. He gives them pure Dietrich Blood, but when going through the transformation process, it is as if the blood already in the body is fighting against the incoming blood, causing some of the Pure Blood to be lost and lowering the level of purity.
In people whose blood didn't fight too hard, it stayed too pure, as was the case with Mr. Hoffman, who has the purest Dietrich blood of those present, even above his father's level.
This depends, to a large extent, on the person's abilities and control of their inner body. Mr. Hoffman has devoted himself to reading for too long and has spent a lot of time studying himself, which is why he is so good at it.
