Tessa Ardillo del Relampago is the older (by a year) sister and classmate of Team Krimson's leader Dominic. She showed a lot of promise during her freshman year and her outgoing and energetic attitude easily made her quite a few friends. During that year's final exams she was matched against friend and rival Andy Castillo, a top-rated aron, in a classic match of speed versus power.

Tessa had control of most of the match, using her quickness and electrical attacks to wear Andy down. With frustration setting in, Andy made a full-out attack in an attempt to end the match quickly. Tessa moved to dodge but lost her footing and took the hit hard. She landed very awkwardly and didn't get back up. Andy's celebration of his victory didn't last long though as it became very obvious that Tessa was badly hurt.

Tessa suffered a broken back from the hit and fall and was paralyzed from the waist down. It was nobody's fault, but one of those rare and unfortunate accidents that can happen in any contact sport. Although she never blamed Andy for a moment he never forgave himself and to this day has never battled again. As for Tessa she returned the following year with a new focus in becoming a coach and trainer.

Tessa has a very good eye for spotting flaws and weaknesses in a fighter's style, but unlike some others who selfishly exploit such talents she shares her knowledge with her fellow students and helps them overcome these flaws. She currently serves as student assistant coach to Coach Michael Marceau, a position many girls at the school envy, and is often consulted by other students looking for that extra edge.

Tessa is a very outgoing and friendly girl who hasn't let her accident slow her down or consume her life and remains physically active as much as possible. Tessa is single but on the prowl, with her eye on a certain "extreme" psychic waterfowl. Although he's spoken for, it doesn't stop her flirtations, which causes him no end of chagrin. Recent developments in electrotherapy have given her new hope and she has regained some slight feeling in her legs. She has vowed to walk up to the podium to receive her diploma when she graduates and intends to return to battling at some point. If she ever proves physically able to do so, she will be more than mentally ready.