Pollux

Pollux is the son of Dionysus and the twin brother of Castor.

The Battle of the Labyrinth
Pollux sees his twin brother, Castor, die in battle. At Castor's funeral, Pollux tried to speak for his brother, but couldn't choke out the words due to his grief. He lit the funeral pyre, and walked away, trying not to cry.

The Last Olympian
In The Last Olympian, Pollux is the only member of his cabin. He fights bravely in battle, calms the other demigods down when they are worried and anxious about the spy amongst them, and is shown to be a good warrior, and have common sense.

He breaks his arm in battle, and Percy insists he not get back into battle, but doesn't tell him why. Dionysus specifically requested that Percy keep his son safe, and Percy didn't want to embarrass him by revealing it.

Personality
Pollux is level-headed, and a good warrior. He is not very close to Percy, Annabeth, and Grover, but is very brave. He was willing to fight with his left hand, though he is only practiced in his right, which would be suicide.

Appearance
Pollux is blond, with a round face like his father. He is very good-looking and has an athletic look. He and his brother, Castor are/were identical.

Relationship with Castor
It is shown that they were very close, and that they loved each other very much. Pollux was brokenhearted and crestfallen at his brother's death, and this helped his fury against Kronos and his monsters, so he had no doubts about him fighting for his brother's memory.

Abilities
Pollux can control the states of the mind, and control grapes and strawberry plants, using his powers he can grow vines and use them for various things like grapples or restraints, just like his father, except his powers are not restricted. He and his father are very much alike.