Personalities in Tabitha
Excluding the main personality of the girl, four others have appeared since her breakdown in the wastelands. As revealed by Colleen, each one of them has to be given a name for them to remain a separate part of Tabitha's mind. To not have one would cause that entity to fade away and expire.
Newt
Presented as the youngest of the inner voices, Newt was 'created' pre-unification as a desire to have a childhood. As such, the girl pictures herself as a small child and acts accordingly. When exposed to magic or attention is brought to her reflection, Newt will use the Dread Dagger's ability to change her appearance to match what she sees in her mind. Of course she sees herself as a very young child, somewhere in the single digits in human years. Due to this she's placed Tabitha in embarrassing situations multiple times as her transformed body and emotions seem to match her appearance instinctively. Currently due to regular nightmares Tabitha finds herself waking up in the young girl's form much to her discomfort.
Newt shows no ability to fight or defend herself. What skills she possesses, beyond the ability to change her appearence, is currently unknown. Originally she was referred to as Tabby, a common nickname for Tabitha. Johnny came up with her new name while arguing that Tabitha's name was Tabby - not anyone else.
Colleen
Named by Xue Qian, Colleen is the second personality to spawn from Tabitha's breakdown. Picturing herself eternally bound in a straight jacket, this personality at first seems to have no idea who she is or how to control her abilities of which chaotically begin to manifest on their own when she becomes the dominant Tabitha. Often her fire and shadow abilities dance across her skin in a bizarre show of darkness and flames. Recently it was revealed that her lack of memories stems from the other personalities being 'awake'. In her own words she represents "the forgotten" and as such can only access what the rest of the girl's mind cannot.
Tabitha rarely considers the magical abilities she got from Sun when she was created and as such Colleen is the most powerful magic user of the group. However, controlling it is another story and the reason she's rarely shown using it.
Meria
The third personality to make an appearance described herself as 'the first, the original'. When Tabitha was first created by Johnny C she appeared as an undead version of Samantha intended to drive Sun into doing his bidding. As such this malicious personality takes the credit for murdering the original as well as most of the horrible things Tabitha has done since her creation. Unable to name herself, Meria took Samantha's name and began to intentionally pick fights wanting to cause the body to die taking all of the voices with her instead of fading away alone. This was later brought to an end by Caliga who decided her name just to put a stop to it. Even still, she remains the most hostile of the group and picking on Newt continues to be one of her favorite activities.
Being the closest to Johnny, she also retains the most amount of control of their shared wastelock based powers.
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The fourth personality was spoken of by Colleen as the one who sleeps and should not be woken up. This personality, which caused Tabitha's breakdown in the wastelands, identified itself as Johnny's Wall Beast. This would imply that it was the chaotic entity that brought the Doughboys to life if it where true. More likely it is just a being of similar nature. Colleen implied that this fourth personality already has a name, but that name has not yet been revealed. While this entity is clearly the one which nearly destroyed Caliga in the wastelands, it was discovered by Sun to have a weakness to time. So much energy is burned off by this personality that it collapses after only a few minutes, leaving a battered and bruised Tabitha unconscious in it's wake.
This personality is dangerous enough that the other four versions of the girl agreed to hold a truce from fighting with each other just to prevent it from waking up again. How long they can keep that up has yet to be seen.