Tarrant's origins involve him with the Hightopp Clan, which was destroyed by the Jabberwocky, sent by the Red Queen during a visit by the White Queen to their village on the "Horevendush Day". Though the White Queen was safely spirited away, the Vorpal Sword (as well as her crown) was lost in the confusion. Tarrant is the only member of his clan left- everybody and everything else was killed or burned to the ground. Tarrant only escaped the destruction because he led the White queen's panicked horse away from the initial attack. He returns after to find the village burnt to the ground, a shocked look on his face he bends down to pick up his trademark hat. When we next see his face it is clear from the half smile that his sanity has shattered. A scene of Tarrant's past can be seen-the Jabberwock blowing fire down on the clan, when he and Alice are traveling and they pass through the remains of his home, causing him to briefly flash back to the destruction.
The destruction of his clan broke something in Tarrant's mind - causing him to become detached from reality and also develop a slight split personality. When he becomes upset his eyes change from green to a golden yellow and he begins speaking in a noticeable Scottish brogue. Tarrant can become violent in this state unless someone snaps him out of it. Mallymkun the Doormouse snaps him out of it the first time by shouting, "Hatter!!" when he is about to attack the Chesire cat who he blames for the attack on his clan. Alice later snaps him out of one of his episodes when he is imprisoned at the Red Queen's castle making hats. Tarrant himself is vaguely aware of his personality problem telling Alice that he has to get out of the Red Queen's castle saying its getting harder for him to think clearly there.
The Mad Hatter, named Tarrant Hightopp, first met Alice when she was a young child at the age of seven. They became friends quickly, even enjoying tea together. Alice forgot these memories while she was away from Underland, but at the age of nineteen, Alice falls down the rabbit hole again. She has no recollection of Tarrant when she rediscovers his tea table of friends and joins them in their rebellion against the Red Queen. Tarrant quickly tries to help Alice, especially when the Red Queen's minions come to him looking for her. He gives Alice a potion that shrinks her, then hides her in a teapot and pretends that he's never seen her, even after being choked by the Red Queen's Knave of Hearts, Stayne.
After Stayne leaves, Tarrant takes Alice on a journey to Marmoreal and explains the Red Queen's reign of terror over Underland on the way. Soon, the Red Queen's minions pick up Alice's scent and start chasing them. With no other options, and the enemy approaching, Tarrant puts Alice atop his hat and flings it across a river to the opposite side (saving her from the Red Knights), but then draws attention to himself and gets captured in the process. He is taken away as Alice watches on. Stayne tries to toture him for information on Alice's location but his insanity protects him from the torture methods.
When Alice arrives in Crims, Tarrant is brought into the throne room, and decides to distract the Red Queen from executing him by hatting her. During his time as her prisoner, he makes many hats for her to try on. However, when the Queen tries them on, she hates all of them.
After Alice is discovered and escapes, Tarrant is ordered to be executed. However, at the execution, he and the Cheshire Cat work together to help him escape-the cat disguises himself as Tarrant using shapeshifting abilities and his hat, thus leaving Tarrant free. After the ruse is discovered, Tarrant angers the Red Queen by turning her people against her, then retreats to Marmoreal. There, the White Queen decides that they must have a champion to destroy the Jabberwock. When Alice, the prophesized slayer of the beast, she doesn't step up, Tarrant is the first to say that he will do it. Alice, however, is the only one that can defeat the Jabberwock, and no one else can take the position. Alice shockingly arrives and is ready for battle against the foul beast. They march towards battle.
The Red Queen quickly sends forth her champion, the Jabberwocky, and so Alice steps forward as well for the White Queen. The battle between the two begins. However, Tarrant quickly interferes with Alice's battle with the Jabberwock and starts a war between the Red Queen and the White Queen's armies. Stayne draws his sword, and he and Tarrant quickly engage in a sword fight. Not long after, Tarrant disarms Stayne and knocks him to the ground, raising his sword above his head, and ready to impale Stayne. Tarrant nearly kills the Knave, but is stopped when he notices Alice slay the Jabberwock. He then throws the sword aside, disgusted. After the battle, and victory, Tarrant celebrates with his famous dance. Alice chooses to leave Wonderland later, to the sadness of Tarrant. He bids her farewell, and she leaves but she promises that she will return.