Wands are truly mysterious instruments. Their curious ability of finding the perfect counterpart and the wondrous ways in which they interact with each other are features that set them apart from other magical objects, as it implies a degree of sentience.
Constructed from the many wand-worthy woods - holly, yew, and blackthorn to name a few - wands are created with the greatest possible care by wizards who are learned in wandlore. Within every one of them, there exists the essence - in the form of a hair, feather, or heartstring - of a magical creature. Usually a Phoenix, Dragon, Unicorn or in rare cases Veela. In the case of the Elder Wand, however, the core contained the tail hair of a Threstral.
With wands in hand, witches and wizards can more easily accomplish the more mundane tasks of daily life: washing cauldrons, mixing potions, cooking dinner, etc. Additionally, wands have the capacity to aid in tortuing a person, causing pain, and worse, death.
Could wands be a conspirator in such an act like committing murder? Most in the wizarding world have it as fact that it is not the wands themselves that do these things; it is the wizard who releases the magic. It is common knowledge, in fact, that all the wand really does is provide the focus point and, perhaps, a magnification of the spell employed (or is it a de-magnification?) Maybe more poweful spells are possible if the user employs "wandless magic."
"Wands do indeed absorb the expertise of those who use them." -Albus Dumbledore, The Tales of Beadle the Bard
Dumbledore was, at the time, writing about the Elder Wand. In truth however, he was speaking to wands in general. Dumbledore is suggesting here that wands have some degree of retention as they pass from one hand to another. Perhaps it has something to do with the inherent resonance of a wand with its carrier. Along those lines, it would appear as if there exists a longing within the wand to be a partner in whatever deeds the carrier is committing him or herself to.
Take, for example, the Elder Wand. Its past owners have had cold, ruthless spirits and have been generally violent duelers. So, is it not conceivable that the Elder Wand itself has developed a strong affinity for murder?
Committing murder and causing pain can be done in the world of Harry Potter simply by muttering a spell. These unforgivable curses, we are taught, require complete certainty on the part of the spell caster. In Order of the Phoenix, Harry could not cast the Cruciatus Curse. Perhaps it was not only because he didn't feel the cold spirit within him, but also because it did not exist in his wand. It would seem an act of violence as to kill another person requires perfect agreement between the wand and its master.
But what if a wand does not like its master? The loyalties of wands seems fickle enough, considering they can be "won" if somebody else comes along and "beats" their previous owner; but Deathly Hallows is rife with wands that do not perform properly for their apparent masters because they really belong to another. What is the nature of this relationship between master and wand? Sometimes it seems like enslavement, at other times like a great love affair. Or is it possibly both? . . .