The Fanmade Characters-
Note: The original Kaito may sometimes be identified as Kaito Shion (始音カイト/始音KAITO Shion Kaito), Shion being his assumed surname; it may be carried by his "siblings" as well. (eg. Kaiko Shion, Akaito Shion, and so on.) This is originally Kaito depicted as updated to VOCALOID2 standards, artwork and voice-wise.
Akaito (アカイト) is the younger 'twin' brother of Kaito. He uses an octave lower voice than Kaito, and has red clothing, as well as red hair. His item is a Habanero Pepper, and is depicted at least once to have interest with Neru, though some assert that he is in a romantic relationship with Muri Anone or even Mikuo Hatsune. Two variations of Akaito exists; a mere color-swap with Kaito, and another with his coat colored black.
Kaiko (カイコ) is the sister of Kaito, presumably the youngest in their family, using an octave (sometimes two) higher than Kaito. She is almost a female replica of Kaito. Two designs of Kaiko exists; one is the original Kaiko inspired from the anime and game Idolmaster (complete with a diagram), while the other one is a variant of Kaito's clothes. Kaiko sometimes uses her brother's assumed surname, Shion.
Kikaito (キカイト) is another brother of Kaito, who uses two octaves lower than Kaito and wears yellow. Unlike the rest of his brothers and sisters, he has a very robot-like body, as shown in these two pictures. His item is a lemon cotton candy.
Taito (Japanese: 帯人 Taito Chinese: 白隴 夏)is another brother of Kaito's. He has a higher pitched voice and his color scheme is purple. His items are bandages and an eyepatch, while he wields an icepick as a weapon. He is a Yanderoid, and he has violent tendencies, especially when provoked. Often depicted as wounded and sometimes bloodied, but not exactly weak, and his injuries is assumed to be the result of his violence. This, and this is how he looks like.
Akaiko (アカイコ) is the red-clothed version of Kaiko. She is equivalent to what Akaito is to Kaito. This is what she looks like, though there are numerous variants of her outfit.
Here is another picture, which is Kaiko Recoloured.
Kikaiko (キカイコ) is the yellow-themed version of Kaiko. She is equivalent to what Kikaito is to Kaito. This is what she looks like.
Nigaito (ニガイト) is another addition to the Kaito family. The sleeves on his coat are longer than his arms. His color scheme is green, and he is known to be very shy. Here is an image of him.
MoKAITO (モカイト) is a brown-schemed version of Kaito. His name comes from 'mocha', which is pronounced 'moka' in Japanese. As evidenced by his name and color, he likes coffee, but also enjoys hot cocoa with milk and sugar. He likes it this way because the 'smoothness' helps to keep his skin smooth as well.
Mekaito (メカイト) is a giant Hachune-ish version of Kaito.
Kamaito (カマイト) is Kaito as a drag queen. His name comes from combining the word Okama (お釜 Okama Lit. Transvestite) with his name. He wears makeup, a purple feather-lined jacket (often mistook as a boa), and a long blue dress with slitted thighs. Here is an image of him.
Meito (メイト or sometimes 咲音メイト Sakine Meito) is the male version of Meiko carrying a masculine version of her voice. Sometimes he also carries his sister's assumed surname, Sakine. This is how he looks like.
Meiko Sakine (咲音メイコ Sakine Meiko) is "the younger Meiko that came out to music trend at 16 years of age" (not the Meiko of younger version but Meiko when she was young) created by Nanameue-P. The original Meiko sometimes use "Sakine" as their surname as well, including other related derivatives like Meito.
Miku Hatsune-based Vocaloids
Miku is notably the source of many Vocaloid derivatives; Haku and Neru came from Miku, for instance.
will try to be online more, its been forever! </3