Terra finally understood why she went to Slade. The Titans knew she betrayed them for control, but they didn't know everything. Terra knew she came to Slade seeking solace. He could help her. He didn't care that she had destroyed every city she had lived in. He comforted her by putting that 'habit' to use.
Now, she was in charge of the city. Another notch on her belt. But there was no comfort. She knew Slade was using her. And for some reason, it comforted her. She was seeking solace, and she found it. Not in Slade, but in destruction.