When Niko first meets Gerry, he is heavily inebriated, making him very capricious. He belittles his brothers and Michael Keane, a friend of the family. Immediately after, he warns Niko to never hurt his family, or he will hurt Niko's.
Later after that mission he calls Niko saying he has work. Niko comes over to visit a now-sober (and somewhat less hostile) Gerry. In the mission, Undertaker, it's shown that he was taken to jail. After the funeral he calls Niko saying that he has him on the visitors list at Alderney State Correctional Facility. He tells Niko to kidnap Gracie Ancelotti, the daughter of Giovanni Ancelotti. Even though Gerald harbors hopes he will be released from prison, the charges against him prove to be more severe than he knows. Gerald bids farewell to Niko, as he will be spending a long time in prison.