Long ago in an earlier age, there was only water where islands now lie. One day - for there were day and night by then, though humans did not yet exist - a great serpent grew tired of swimming and decided to rest. It drew the earth up around itself, and so the island was born. Other stories say different things - in particular, Volcano Looming High has its own account - but stories do not need to agree for them to be true. Regardless, many spirits can sense the immense serpent deep below. It is mostly asleep, and its influence on the land above is limited, but the Invaders' Blight already begins to sting it towards greater wakefulness.
Put 1 on your starting board in the land #5.
There are several ways to play the Serpent, but all require patience: early game involves slowly building up Powers and Presence. It's not helpless during this time, but it isn't as effective as anyone else. It becomes incredibly powerful after awakening, but getting there requires a lot of time. Make sure to Absorb Essence before you run up against your Presence cap - and to get other players' buy-in before using Absorb Essence on their Presence.