Because he’s incredibly fun to watch, climbing his way to the very top with his pure wit alone, he always says just the right thing to turn the situation to his favor, like when he was captured alongside Jim Gordon and Harvey, and his 2 biggest enemies at the time Fish and Maroni, are staring him down, with one sentence he turns them against each other and makes his escape, it’s brilliant. Also because while he’s clearly extremely selfish and definitely evil, he’s not a monster even despite being a villain character, like him showing such love for his Mother which is honestly pretty sweet, or like when the Haven was blown up he could only really stare in horror, showing disgust towards other supervillains or how he was disgusted by Selina Kyle having fingers on the table next to her when he came to see her asking for help about his belongings being stolen, on top of that he’s straight up saved Jim Gordon and many others so many times, along with the whole city once, he’s definitely not a good person but he’s a really well written character and he’s done a lot for Gotham, for better or worse