Well, I have seen that these are the most common, so I will destroy them one by one, if there are more, please let me know.
.HE TRIED TO PREVENT JEROME FROM KILLING PEOPLE.
1. He never tried to prevent Jerome from killing anyone, in fact his first instinct was to leave all those people to their fate, it wasn't until Bruce told him that maybe with his help they could kill his brother, that he decided to leave his bunker. (And yes, Jeremiah if he wanted to kill Jerome, but starve him, and how it didn't work..)
.REFUSED TO MATR A JEROME.
2. He never refused to kill Jerome, he even tried to, to distract him so he wouldn't see the police attack coming, who clearly wanted to kill him.
.HE TRIED TO FIGHT AGAINST THE RELEASE GAS.
3. He tried to fight it, because it is a natural reaction of our body to fight anything unknown that enters our system, none of it was conscious. (There's also a photo that shows Jeremiah smirking after the laughing gas, not to mention that even if the gas changed him, it's irrelevant, since in 5x12, his eyes are completely normal, his white skin almost obliterated, so much so. that I need to apply makeup to achieve a white face and painted lips, he himself decides on his own to continue with his atrocities, so that we would find ourselves with a situation similar to Batman Who Laughs.You cannot redeem someone who does not want to be redeemed .
HE APPRECIATED ECCO AND CARED ABOUT HER.
4. With the case of Ecco... How would you feel if one of the best toys you ever had, is lost (Like when Ecco was hypnotized in 4x17) or stops working? (Ace in 5x12).
Jeremiah calls her MY sweet Ecco, also MY ECO. As if she was a reflection of his will from him, or at least she was.
FOR BRUCE, HE IS SIMPLY A VICTIM OF JEROME.
5. In Bruce's case, he will always see Jerome as the victimizer, or at least to a certain extent, and that will make The Joker always win, unless Bruce realizes that he doesn't need to heal or recover his friend, but to convince him that he is wrong, that he needs to change, that he knows what is best. When Bruce is in the same boat of thought as The Joker, he can then properly confront him.