In "The Judge", Red goes to see an old friend and Annapolis roommate from before he became a criminal for information. Said friend lost his job when Red defected and more or less had his life ruined. In exchange for what he needs, Red offers to help him get his life back together with the help of some 'friends' of Red's. Those 'friends' turn out to be Harold Cooper, who agrees to see what he can do.
Harold trying his best to comfort Ressler in "Mako Tanida" after Audrey died due to massive blood loss when she was shot by Tanida in the stomach.
The final few minutes of "Ivan".
Reddington goes to visit Harold, recovering from his house in "Lord Baltimore" and tell hims that there's nothing bad about his crippled state after nearly being killed by Berlin's assassins.
Harold goes out of his way to tell Liz that he's available to help her for moral support ever since the events of the first season in "Dr. James Covington".
In "The Front", Samar becomes exposed to a lethal virus. Liz decides to risk her own life to keep Samar company so that she won't have to die alone. Naturally, a cure is found in time to save both of them.