Her strength increased as it tightened further around the neck of Joe for longer until she finally began to feel something stirring within her.
The connection between herself and Joe broke completely and then what followed was the new surge of power that came with it.
The Life Energy that was gained was not nearly as much as what she obtained from Cal, Eric and Terrance but it was still quite a lot.
She had felt that there was quite a difference between those who knew they were going to die and struggled to live as opposed to those who were dealt with quickly.
They were able to feel the flashes of fear as they neared their death resulting in more Life Energy being extracted from them.
Others like Tom had died much too early to experience such intense feelings so they would not provide a great deal of fear through the connection.