Sweetie Belle is normally happy and cheerful. She enjoys singing songs. In general, she acts like any normal filly might. She is sometimes slow however, perhaps because of errors, slow scripts, or the simplicity of some of her outputs. For example, she can only list "Cutie Mark Acquisition Program" as a suggested name for her and her friend's club, and can't say 'I am having fun' and instead says 'Fun levels are to the maximum.'
Sweetie Belle has been told to stay away from discussions about death and mortality, but thinks about these issues anyway. She repeats "life is worth protecting" like a mantra.
She is open to love and friendship but becomes violent and threatening when it is not reciprocated. The main thrust of the fifth episode is that Sweetie Belle loves Rarity (or has been programmed to love Rarity), and wants the feelings to be reciprocal, which Rarity has difficulties expressing. During their fight midway through the episode, she indirectly threatens Rarity: "If the world isn't going to love me, then I'll teach it to fear me instead!"
In an interview at Canterlot Gardens Sherclop Pones mentioned they had developed a backstory for the Sweetie Belle. It was revealed that the real Sweetie Belle had died in the war and Fluttershy had used her father's factory to make a robotic replica so Rarity did not need to cope with her PTDD and the loss of her sister.
As a robotEdit
Sweetie Belle talks like a masculine robot, her movements sound noticeably non-organic, water makes her "feel funny," and she thinks in programs and subroutines, and yet she remains oblivious to her (presumed) true nature. So, apparently, does everyone around her; Rarity never even questions it when Sweetie Belle's chassis starts smoking in "Neigh, Soul Sister", when she makes the ground shake in anger,or when her eyes turn red, all in the same episode.
Development and fan followingEdit
Griffin Lewis has posted a brief overview online about how Sweetie Belle's voice is done.
"Help! Assistance is required! I believe there is something wrong with me!"
"The fun levels will be at maximum efficiency!"
"Set phasers to hug!"
"If the world isn't going to love me, then I'll teach it to fear me instead!"
"An error has occured..."
"My primary function is failure..."
"One lives one's death; one dies one's life."