Albert 'Chamo' Chamomile is a perverted, lingerie stealing, chain-smoking and talking ermine - an ermine elf, akin to a Caith Sith. (Though he has a long, and prehensile tail.) Negi freed Chamo from a trap when he was five years old. Since then, Chamo has been going to Negi whenever he ran into trouble, attempting to provide him with some help and advice.
This time, Chamo appeared in Japan after jumping through the barrier, he claimed to have been sent to Negi by his foster sister to help him find a partner, though it was later found out that Chamo escaped from the law for stealing over 3,000 pairs of girls' underwear, and fled to Negi because the law could not arrest him if he were the familiar of a wizard.
He lied to Negi saying he stole them to keep his sick sister warm, which Negi promptly believed, whereupon Negi made Chamo his familiar. (As a side note, being turned into an ermine is one of the punishments that Negi's magic academy gives, although Chamo is actually a type of elf/fairy/Cait Sith).
During his arrival at Mahora, he stripped nearly every girl in the bathing area of her swimsuits. He had also fibbed about being sent by Negi's sister to help Negi find a partner and immediately pointed out Nodoka to be the prime candidate, (an obvious lie at the time, though it is somewhat ironic that she later becomes one of Negi's partners).
He later confronted Yue on her feelings toward Negi, and then urged her to make a Pactio with him, which she eventually did. He has also played a hand in getting Pactios with Konoka, Setsuna, and Haruna, though with Haruna, this may have been out of pure greed to get more Ermine Dollars. Later in the MahoraFest Arc, Chisame was also slowly convinced into making a pactio with Negi.
The more recent Pactios made are with Kaede, Ku Fei, Chachamaru, Ako, Makie, and Yuna. Negi had a pactio with Theo, the third royal princess of Ostia, but Negi was the Ministra in this particular case. As it was only for the duration of the match between him and Jacobus Rakan, it has since been cancelled.
Chamo cares strongly for Negi and will fight to protect him, but he is not above using him to try to make a fast buck. Chief among those methods is attempting to make probationary contracts between Negi and as many of his students as possible, since the act nets him 50,000 Ermine Dollars per contract. The most prominent attempt was the "Kiss Negi" game he set up in Kyoto with Kazumi, which he rigged with a magic circle around the inn, so that anyone who kissed Negi would trigger a Pactio. The result was one Probationary Contract with Nodoka Miyazaki, and four botched ones (Ayaka, Ku Fei, Makie, and the Narutaki Twins).
His knowledge of magic and such is vast, and he is very resourceful in making up attacks on the spot. For example, his "Ermine Flash" which consists of him setting alight flash bangs with his lighter as a means of distraction. He seems to have considerable computer skills, (such as ordering items online at mahou.net). Chamo acts as Negi's trusty advisor in most things, though there are times his judgement and/or advice leaves much to be desired...
He normally suffers Asuna's wrath whenever his schemes are discovered or he is caught in one of his perverted acts. Chamo addresses Negi as "Aniki" (big brother) and most of the ladies (like Negi's students) as "Ane-san" (big sister, sometimes with slight variations like "Ane-go" and to Nodoka as "Jochan") even though he is most likely older than all of them.
His level of magic is not as great as some of the others, though he has shown some considerable spell casting, chief among them is drawing up magic circles, which is essential for creating Pactios, and casting anti-telepathy spells. He also has the disturbing hobby of keeping track of the girls' feelings for Negi, often to the chagrin of all involved.
- Chamo's name, combined with Negi's comes from a Japanese saying: Kamo ga negi wo shotte kuru (鴨が葱を背負って来る), which can literally be translated to: 'a duck comes bearing green onions'. The term comes from a legend about such a thing happening, and is used to describe a sudden stroke of good fortune (not only have you got dinner, it's come with it's own seasoning!). Kamonegi, the shortened version of the saying, is also the japanese name for the Pokemon Farfetch'd, a literal example of the saying.
- Chamo is somewhat a pervert liked Jiraiya from Naruto and Kon from BLEACH. Also, both are shared relationship with the protagonist.