Okay then. Let me share this theory with you.
I think Serge being the Arbiter has a deeper meaning. I think Serge in the future is meant to find the Frozen Flame, which would somehow lead him to the TD, and cause him to cause the TD to evolve another step. You want in game evidence? Here you go:
Water Dragon: Wilt thou change this world... Or wilt thou change thyself? Wilt thou live with thy mother planet... Or wilt thou turn thy back on the planet and tread another path?
In Terra Tower, Serge is oddly entranced by the Flame.
Kid: Hold on! Don't touch it!
And then, there's the fisherman in Arni Village, which makes a very intresting comment about the nature of the ocean, which can be interpreted as the nature of the TD:
You'll find the sea to be vast, deep... full of strength and energy, yet kind and gentle. Once it becomes angry, it can turn into the most frightening monster you've ever seen, engulfing everything. Can you hear the cries of countless men swallowed by the sea? The hidden secret the sea whispers? I recommend you learn to sense the mood of the sea. That's if you don't want to join the fellows already at the bottom.