SPOILER SPOILER SPOILER
At that point, as you said, he had nothing: kicked off the force, tried and about to be imprisoned for killing a murderous junkie s**theel. Michael showed him he was valued, that he regareded Neri as a hero, that he wanted to recruit him. Michael at his most brilliantly manipulative.
Agreed... but dont think he really had to "manipulate" Neri as he did others... Neri was assigned a "value"(by Michael) and Neri ran with it.
