Question

How does Percy suspect That Ares wasn’t acting alone.he was taking orders from someone

Answer 1

Because when Percy questioned him, he wasn't paying attention and was in some kind of trans (I don't know how to spell it) and when Percy asked what that was about, he said he didn't have dreams and then Percy said that he didn't mention any dreams

Answer 2

He does not seem to know the full plan. He is also doing what seems like random tasks that have no point. Ares also mentions dreams that sound like the ones Percy had.