Alexis is friendly, caring, and lacks the condescending attitude that most of her Obelisk Blue peers share.
In the first season, Alexis grows Interested in Jaden Yuki's dueling skills, after seeing how Jaden drew Monster Reborn and could have won his duel against Chazz. She challenges him to a duel, promising that if he wins, they won't tell, and if she wins, they get expelled. Winning through the use of "Elemental Hero: Thunder Giant", she concedes defeat and keeps her word.
Later she reveals that she has an older brother while visiting the Abandoned Dorm. She gets herself kidnapped by a mercenary hired by Dr. Crowler. Jaden duels and beats him, freeing her. Shortly after this, she and Jaden become closer friends after Crowler once again attempts to expel him and Syrus, this time in a tag duel Alexis is trusted with one of seven spirit keys. Watching Jaden defeat a duelist named "Nightshroud" who later turns out to be a brainwashed Atticus (her older brother), she learns that he has no recollection of anything in his past and must beat a revived Titan in order to restore them, which she eventually does. She later also meets her old friend Pierre.
Later she loses her Spirit Key to Amneal until she is freed by Jaden.
Near the end of the arc, Chazz confronts her about his feelings and challenges her to a duel. Although making his feelings heard, Alexis shoots down every attempt. She ultimately wins by using "Cyber Angel Benten" and thus introducing her "Cyber Angel" series.
After the first season, two major things happen to Alexis. The first event is her finally confronting her brother to a duel (and winning), to tell him to back off and let go of his dream of becoming a pop duo. The second major event is a temporary drastic change of character due to being brainwashed by Sartorius into joining the "Society Of Light". She develops a more cold and arrogant personality and throughout this season, struggles trying to free herself from Sartorius' grip and when she finally does, has her memories stripped away in order to suppress it.
She regains her memories after losing to Jaden in another duel, albeit having no memory of ever joining the Society.
During the third year, several students come from around the world to study for a while at Duel Academy. In this season, Alexis' role is more or so brought down to watching on the sidelines, but she does help defend the school by battling Duel Ghouls and later comes to Jaden's aid when he becomes persistent in searching for Jesse. After travelling through a dimensional portal, they end up in a totally different dimension. Jaden, nonetheless trudges on. After falling behind, she comes to the conclusion that Jaden stopped caring for her and her friends and is eventually captured by Brron, Mad King Of the Dark World (a Duel Monsters card in our/their real life). She is sacrificed in order to activate the "Super Polymerization" card.
After being freed by Jaden some time after and returning back to Duel Academy, she notices a change in Jaden. Who has become more rude and abrasive. Hoping to make amends, she invites him to a school party and becomes his partner for a tournament.
Despite winning, she becomes angered as Jaden is flat out ignoring her cards. Due to this, she takes the first chance she got to change partners (in this case with Blair & Hassleberry). But after reminiscing on old times, she takes back the decision and wins the tournament with Jaden.
Shortly after, Truman begins an assault on the school and she eventually falls and is sent to the World Of Darkness, where is forced into an eternal nightmare until Jaden, once again saves them all. After this she decides to finally become a teacher and hopes to meet Jaden again someday.