Vincent Starci is the main protagonist of the series. At the age of ten, he received the Ancient Blade of the Elements, the prized treasure of his family, and with its energies is able to control elemental beings.
Vincent's appearance has changed noticeably over the series. In the first game, he is of average depiction with blonde hair and black eyes, and wears a plain red shirt, black jeans and blue trainers. Super Blade Boy added intricate white patterns to his shirt, whereas Box of Secrets changed his eyes to a green colour and made his hair spikier. Finally, Text Code Backwards completely redesigned him. From here onwards, his shirt is light blue (but retains the white patterns), and he wears an open red jacket along with it. He also wears a silver pendant emblazoned with a multi-coloured gemstone and connected to two large pieces of metal on his shoulders which connect to strands of metal that spiral along his arms.
Vincent was initially depicted as a stereotypical silent protagonist in the early games. In Box of Secrets, he was given dialogue, being depicted as a kind-hearted individual who cannot ignore those in need of help.
Sophia Starci is Vincent's wizard-like sister. Introduced in Super Blade Boy (albeit referred to as Sophie in this game), she served as a minor supportive character, although in The 64 Threats she was given a more significant role, in which she helps Vincent pinpoint the locations of the 64 Threats.
Sophia was initially depicted much like Vincent, being ten years old with an average appearance. She had long brown hair and black eyes, and wore a blue wizard's robe with plain brown boots. Box of Secrets gave her orange eyes and shorter hair, although in Text Code Backwards her robe was much more detailed, her hair was lengthened and she wore a wizard's hat that matched her robe. This design was kept consistent for the rest of the franchise.
Sophia is quite shy, often fearing her incredible magic powers. As the series went on, however, her more carefree side began to show more and more.
Christopher, last name unknown, is Vincent's best friend. Making his debut in the third game as an implied character in the manual, his first legitimate appearance was in Box of Lies as a character who gives tips to the player. In Four Elements and all future games, he was a playable character in the Minigames and could help the player by giving information on their Elements.
Christopher is roughly eleven years old, with white hair and black (later purple) eyes. In The Art of Blade Boy and Box of Lies, he wore the same attire as Vincent, albeit with a yellow shirt that possessed blue patterns, green trainers and a red belt with intricate black designs. Four Elements redesigned his attire, giving him a plain blue shirt, yellow jeans, dark green trainers and a plain red belt. He also has pale blue markings all across his body (although these markings can only been seen in full by hacking the game), which he supposedly received in a paint-based accident.
Christopher is fairly relaxed, not worrying when even the direst of troubles show up. He is also shown to be very knowledgeable about the world around him.
Samantha Ecnelis is Sophia's best friend. Her existence is more or less implied, as she never speaks and is never seen in the series.
The Emphases (singular Emphasis) are telepathic Elements, who are considered vastly superior to other Elements of their kind. Vincent has four Emphases as travelling companions, those being Wind, Fire, Water and Earth. It is confirmed that humans can only understand the telepathic musings of Emphases using the Ancient Blade of the Elements. Sophia, however, is also able to understand them, although this is likely because of her magical talent.
There are four known Emphases - two male (Wind and Earth) and two female (Fire and Water). The Emphases went through drastic changes over the years. At the start of the franchise, each element was depicted as a small sphere of appropriately coloured light (Wind is yellow, Fire is red, Water is blue and Earth is green). In The 64 Threats, they were redesigned to be human-shaped, with proportions roughly matching those of a chibi character, in addition to possessing noticeable eyes. When Text Code Backwards came out, they were given more detailed appearances and crystal spikes that replicated hair.
The Emphases are somewhat mischievous and only answer to those with power over them (i. e. Vincent). They are shown to like being cared for, particularly by Sophia, and have insurmountable magic which is said to be great enough to tear through the fabric of existence.