Jacob is a Roman demigod or legacy at Camp Jupiter.

The Heroes of Olympus

The Son of Neptune

Jacob is the Eagle bearer, or Aquilifer of the Twelfth Legion. It's supposed to be a great honor, but given that it involves carrying an empty pole — the Eagle having been lost in Alaska — Jacob is less than thrilled and quite embarrassed by his assignment.

The Blood of Olympus

He is seen holding the eagle.