He was not 'sympathetic to/toward' their cause. [=he did not support their cause]
The book doesn't really have any 'sympathetic' [='likable'] characters.
I didn't find the hero in the movie very 'sympathetic'.
(..) The intervention was a complete train wreck. - Richard wouldn't listen to anyone. - Oh, Paige, I'm so sorry. You're laughing at me? I'm trying to be sympathetic, and you're laughing at me. I'm sorry. Maybe I needed a laugh after what I just went through. Yeah, it's okay. Is there anything I can do? (..)2004 TvShow: Charmed Title: I Dream of Phoebe Season: 6 Episode 15