Wand Core: Occamy Feathers (fanon)
Somewhat rare due to the risk involved in collecting the feathers, and sometimes quite temperamental, Occamy feathers nevertheless make a fine and admirable wand.
Of average power for a wand, Occamy Feather cores are most prized for their great flexibility, while they excel at magic to do with flying and size, they are not really particular to any one field of magic and take easily and quickly to any new magic their owner may attempt. Thus the full magical range of the wand depends almost entirely on that of the wix wielding it.
Occamy Feather wands are a bit jumpy, and may "spook" easily, sometimes firing off a jinx wildly when surprised. Many Occamy wands are able to shrink or expand to fit the available space, much like Occamy themselves, thus they can be as small as a toothpick or as big as a staff.
The ideal owner of an Occamy feather wand is, like the Occamy, uniquely aggressive. Though they are not overly combative and do not go looking for conflict, they react quickly and viciously to any threat-perceived or otherwise-and can go overboard in their attempts to defend themselves or those people and things they care about. This is not due to an inherently antagonistic or hostile nature, but, because, like the Occamy, they had to learn to defend themselves early in life. For whatever reason, an aggressive approach to their surroundings and quick reactions were essential to their survival.
They are also often quick thinking and adaptable, and very opportunistic. With excellent survival instincts and intuition. There is also a tend to suffer from anxiety disorder, and can be overloaded by too much audible stimuli, leading to panic attacks.
"I bet other wand makers are jealous that I can get these bad boys so easy. Pays to be bff's with a magizoologist, just saying." -January Hawkins, Resident Smug Prick, Ilvermorny School of Witchcraft and Wizardry
(I got the idea for the size-changing thing from @cloverywands)
Image from harry potter wiki