Jack had been thinking about trying to strengthen his soul bonds with Madison and Miranda so he could talk to them mind-to-mind, like he could with Samantha, Katie, and Naoko, and given that he was currently inside Madison, he decided to try strengthening his soul bond with her.
He focused on his sense of their soul bond and reached out for her soul and grabbed it.
His "soul senses," for lack of a better term, were not as vivid as they were when a new soul bond was forming, but he could still feel her soul well enough to make changes to their soul bond.
He pulled her soul closer and mentally hugged her soul, like he had done with Katie, and focused on trying to form a mental connection to Madison.
Of all the people he'd soul bonded, Madison was the only one whose soul took an active role in the soul bond formation process. The first time, her soul had tried to merge with him, and this time was no different.
