THEY ARE BOTH COUSINS AND KNOW EACH OTHER
Percy convinced Ares to help him by, making a deal that Percy would fetch Ares's shield. In return, Ares would give Percy a ride to Las Vegas and a bag full of goods.
If Percy will recover Ares' shield from a theme park, Ares will give him transportation, information, and food
he is there because ares was hoping that hades was going to get rid of Percy (aka:killing him) but ares is there because he had set Hollywood on fire to blame Percy and plan on killing him by himself but he releases his immortal form (ares) and he escapes.
Percy suspects it when ares is uncommon about licking the lamp post
Percy Jackson stabs Ares unexpectedly in the ankle, which caused Ares to bleed golden ichor, the blood of the gods.
Ares is the God of War in Greek mythology and in the Percy Jackson books. Ares is also Clarisse's dad in the Percy Jackson books
Percy wins.
When Percy was confronting Ares and Ares said, "I am a god. I don't have dreams...."
Percy suspects it when Ares is uncommon about licking the lamp post.
Ares hates Percy because firstly he gave his daughter a shower from the toilet as soon as he arrived, and also because Percy stabbed him in the heel. ares still has a grudge against Percy for defeating the god of war in his own game.
Ares makes fun of how Percy's dad saved him in his previous battle with the chimera and calls him a coward.I assume you mean in the Lightning Thief...Ares told Percy that his mother was not really dead, that she was being held captive.
Percy begins to suspect that Ares was taking orders from someone because he notices that Ares is behaving strangely and seems to be protecting something. Ares also implies that someone else is involved when he taunts Percy about the Lightning Thief quest being a setup. These clues lead Percy to believe that Ares may have been working for a greater power.