Response to "Jack July" ending

Jack was a mess, his life was clearly taken over by his drug addiction, which led him to make some bad decisions. Seemed as though he was helpless and was very sad. In the end he went to the one person (Jamie) who would PROVIDED him with what he needed; a meal and shelter. In the beginning of the story we saw that Jack was modified when he realized what had happened between him and Jamie, but out of desperation he turned to him.

I wonder what exactly the narrator meant when he described Jack's feeling as though his "heart leap straight into the man's fat little hand", was he "genuinely falling" for Jamie or him not being able to TAKE CONTROL of his heart because Jamie was so nice to him........