From the top
The younger, but thus far more successful, brother of Derek Arthur Kunze, and uncle to Alrick Kunze. Born November 11, 1986 to Pure-Blood parents who had ignored, in large degree, their eldest son, his middle name was meant as a reminder and warning to themselves of the dangers of child neglect. Likewise the "mistake" of Hogwarts was not repeated, with Steve going to Durmstrang. He manifested Metamorphmagus abilities as a five-year-old, thus redoubling his favourite status in his parents' eyes. It could, in fact, reasonably be said that Steve and Derek did not have the same parents, since Steve's adored, indulged and protected him, none of which was true for Derek.
Dear old . . .
His Graphorn and Blackthorn wand is the product of his own Wandlore studies at Durmstrang, for although Graphorn is a Class B tradeable item, Steve was able to impersonate a Swedish Ministry official (as a Metamorphmagus) and steal it. Despite his advantages in, and talent for, sneakiness, Steve is generally the "take the bull by the horns" type, preferring a head-on confrontation and the attendant collateral damage. He keeps a mental scorecard of the lives he believes he can claim to have ruined or taken (twenty-four and thirty-five, respectively), but no physical mementoes, as these could be used as evidence against him. He tends not to change his features, but his hair and build can both vary dramatically over the course of a single day. He believes, with Emerson, that "A foolish consistency is the hobgoblin of little minds", but applies it primarily to moral standpoints. He does, however, have surprisingly high and consistent standards about some things - for example, he takes no credit for ruins or kills if anyone else played a significant part in the process. He is meticulous, and has seemingly unending patience when tasked to deal with a problem (i.e. kill someone). On practical grounds, he is also a man of his word in his business dealings, at least when it comes to those he's planning to leave alive.
At Durmstrang, Dark Arts, Arithmancy and Potions were his favourite subjects, though he did well even in those areas, such as Care of Magical Creatures, that he didn't really care for. He took Muggle Studies, out of a "know your enemy" desire, and understands the functions and usages of electricity and information technology far better than 99.9% of wizards. Indeed, it is these "Muggle proclivities" that have made him such a sought-after assassin, as he can fabricate Muggle causes of death, or at least mask his magic to make it seem as if some electrical device, or similar, was the cause. His potions skill was, above all, a propensity for poisons, and his home contains samples of practically every lethal Muggle or magical toxin known. He locked these away the one (recent) time his brother (and brood) came to visit. Despite this arsenal, however, he generally prefers simpler and more common poisons, since their presence can be masked or explained in a variety of ways.
His other half
Steve and Cressida have allied themselves with the WHPS, knowing very well which way the wind was blowing, although technically neither has actually joined. Cressida is a small, mousy, unmemorable woman - and a more successful (forty-two accredited kills) assassin even that her husband. She has prodigious Transfiguration, Charms and duelling talents, having managed on one occasion for over three minutes to battle a trio of Aurors to a standstill whilst awaiting reinforcements. It would probably be wrong to say she loves her husband - but they share a psychosis, and mutual needs. Steve, perhaps surprisingly, as an athletic, intelligent, generally good-looking lad, was a virgin when they married, since he couldn't work out what he was supposed to feel, and always ruined "the moment" with some utterly inappropriate comment with every woman before Cressida.
Steve appears to keep Derek around as a constant reminder of his own greatness, enjoying Derek's humiliations and failures to the fullest. He saw a glimmer of potential in Alrick while the boy was at Durmstrang, but Hogwarts has snuffed that out. This is a shame, since he has no desire for kids himself, but wouldn't have minded an apprentice to pass things on to. He and his wife both still actively canvas for work, though he wouldn't take a WHPS target unless the money was truly irresistible. Steve was at Durmstrang when Voldemort wreaked havoc on the Ministry and Hogwarts, and can't see what all the fuss was about. Voldemort seems to him like another petty criminal with delusions of standing. I mean, the man was a Half-Blood, for god's sake. The only time Steve has deviated from a plan once set in motion, was to avail himself of the opportunity to kill and make an example of a blood traitor. Steve couldn't actually bring himself to kill his parents - so he left it to Cressida, whilst he did the same for her. He even conned her parents' old rivals into paying him to do it, only one example of the angles he is always working. Since leaving Durmstrang, he has gone by Steve K. Kunze, letting people believe the K is for Keith, generally, although he spends a huge amount of his time in various cover identities.
Steve has no difficulty with any kind of fabricated intimacy prior to the kill, and generally wishes to see the light fade in a victim's eyes, therefore avoiding the quick kill. He is immensely skilled at NV spells, and likes, where possible, to set a trap the victim will spring on themselves. His abilities with technology breed distrust among many WHPS members, whilst simultaneously making him practically irreplaceable to the organisation, as they are unlikely to find anyone who shares their Weltanschauung with remotely comparable competences in this field, and they've discovered, to their cost, that Imperiused souls often botch something vital. Uniquely among wizards, Steve carries a (shielded from magic) memory chip in the hilt of his wand, and this does in fact have pictures of him in every guise, and with every victim on it. Strips of denatured Graphorn horn have been used to line the 1 1/2" chamber which holds the chip, to protect it from any magical effects.
With the change of appearance, Steve manifests completely different personalities. He can even be honest and good, for the short prelude that leads up to a kill, and his immersion in a role is so total that Legilimency has never yet revealed it. As this solidified schizophrenia takes place, Steve maintains the appearance through any test or provocation, as the surface personality believes itself unique. He often purchases, and discards, a wand to fit the acquired personality. He has a relatively non-materialistic attitude towards anything connected with a task, seeing all elements, except himself, as expendable. His ego always surfaces at least in the wake of the mission, however. Cressida's greater success can be largely attributed to this fact. Steve's defacto polyphrenia may account for his lack of a Patronus - it found no core to latch on to.
Steve is currently on the run from just about everyone - and hating it. He sometimes seriously contemplates emigration, with only the vaguest notion of letting Cressy know. He has formed a questionable alliance with the Shrouded, or more specifically with Shadow, plotting all the time to remove others in his 'line of work' from the membership roll, and the list of the living. He's satisfied himself that his brother is truly dead, which stirred unexpected protective feelings towards Alrick, although those were soon laid to rest when he realised the boy might endanger him. He began at that point to fully develop a plan to remove the last other remaining Kunze. Without the aegis of Shadow's organisation, however, Steve has once more been sent scuttling for whatever rathole he can scurry down.
Blackthorn, Graphorn Horn core 9 1/2" total length (incl. 1 1/2" chip chamber)