The god who stole Zeus's lightning bolt was Luke Castellan, who was later revealed to be the son of Hermes. He did this under the influence of Kronos, who was trying to gain power and return to Olympus.
Ares, on the other hand, is portrayed as a more traditional villain in the book, acting as a typical antagonist to the protagonist, Percy Jackson. He is obsessed with the idea of war and is often shown to be cruel and destructive. He is not involved in the theft of the lightning bolt.