Oreius

Oreius was the brother of Agrius whom together were known as the 'Bear Twins'. They were the illegitimate spawn of a woman who Aphrodite commanded must marry but chose not too instead fleeing to Artemis. Aphrodite put her in a trance and made her love a bear thusly resulting in her monstrous children and hate from both gods. The Bear Twins were described as being eight feet tall, wearing nothing but blue jeans, being cover by shag-carpeted thick brown fur, with claws for fingers, a snout for a nose, and all their teeth being pointed canines. Oreius was depicted as being a little slow (or at least not as dominant as Agrius) as his typical (if not only) dialogue is "he-he". Agrius often tells Oreius to punish himself which entails Oreius pounding his head against a wall or causing other bodily harm. During the time of Percy Jackson's second year at Camp Half Blood the Bear Twins had found employment in Luke Castellan who had alligned himself with Kronos. They traveled with him as his 'assistants' aboard the Princess Andromeda and first came into contact with the titular character and his friends when they were trying to rescue Grover Underwood from Polyphemus. Luke told them their stories and though it was said they like half bloods for food it is unknown as to whether any unfortunate demigod has suffered such a fate. After the completion of the mission both Percy and his friends encountered Oreius and Agrius once more aboard the Princess Andromeda. While Luke matched blades with Percy Agrius was to hold Blackjack and Oreius was commanded to eat Annabeth and Grover. Though he relished the thought he never received the chance as the timely arrival of Chiron and the Party Ponies (a group of centaurs) quickly ended his life with an arrow through the mouth sending him to Tartarus only seconds before his brother followed.

Noteworthy:

It is possible that Chiron himself defeated Oreius, but cannot be confirmed as the book never clarifies just exactly who shot the fatal arrow. Also while being dominant monster characters of the second book the Bear Twins never fight Percy or his friends, though they do hold them captive. This raises questions about an uninterrupted battle between Jackson and the Bear Twins.