Lio is a descendant of a fire nation. A century ago, his family supported Fire Lord Ozai in his war, and even tried resisting Zuko's government after his father was defeated, but failed and then fled across the ocean in order to escape imprisonment. Authority figures of this large family (grandfather back then, then Lio's father, the oldest son) never abandoned thoughts of fire nation's dominance, though they chose a more moderate way - they decided that rather than slowing down the fall of Fire Nation they should obstruct every other nation's ascension after war. With gold they had they set up several banks and factories, and secretly financed numerous anti-governmental movements in Earth Kingdom and Republic city, and later in United Republic and Earth Empire.
Family is currently selling weapons to both sides of war. Family's interests are not represented on political stage - they prefer to act from shadow. Several members of family, like Lio, are acting in field, maintaining war that drains power from both Earth Empire and United Republic.
Lio is familiar with most of existing firebending and fighting techniques. He received a good yet biased education (homeschool) and wanders around, looking for opportunities to serve his family's ideals and multiply its riches, trying to avoid both glory and notoriety.
He is 23, tough-built, yet average-looking young man who was last seen dressed in a long brown coat, carrying a leather bag with supplies.
Positive traits: trained firebender, lightning-bender, trained with various melee weapons; rich, has important connections; adept diplomatist and liar.
Negative traits: mildly racist thus uncommunicative.