A/N: Sorry about the slang; for those who didn't understand it, 'git' is a British insult that is essentially a milder form of 'bastard'.

Furthermore, I apologise for an inexcusable delay even when one takes into account the fact that I was unable to do any writing at the weekend; I can only plea for forgiveness and explain that I had a serious amount of difficulty working out how to end where I wanted to in this chapter, and I'm still not entirely satisfied.

Crucial Pursuit

Shepard hit the ground, hard, but broke his fall with a roll that brought him back to his feet to pursue his target. He was already around thirty metres behind the terrorist, a significant distance in a chase that would make it easy for the hunted to elude the hunter, particularly with cloaking technology. However, Shepard hypothesised that if Walker had been able to use it, he would have done so already, meaning the sabotage of the circuits in his armour had likely also inadvertently damaged the cloak.

The bastard was fast, though; it looked like he'd put no small amount of time into training to move quickly. Shepard, on the other hand, had never had either the time or the inclination to do the same, when he could move quickly enough as it was and he had things he'd rather do with what little spare time he had on occasion; training focussed on combat and general fitness, not on how to sprint for as long as physically possible.

Shepard watched as the terrorist veered off through the door at the end of the platform that led to the stairwell and it hissed shut behind him, forced himself to run still faster, yet as he reached the door, caution brought him to a halt; he didn't want to burst through the door and find himself running into a bullet. Rather than activating the door's control panel, he rested his head against the cool metal for a moment, suppressing his heavy breathing and wishing he could do the same for the noise created by the blood rushing through his head, and strained to listen for any indication of his quarry's whereabouts.

Faint and receding thudding noises, the tempo approximately matching the nihilist's running gait. Good enough.

Shepard stood and quickly hit the console, commanding the door to open and slipping through the gap as it complied-

And immediately suffered a jarring collision with Walker as he launched himself feet-first at the assassin from the stair-rail a level above him, driving Thaddaeus to the ground, slumped against the wall with the corner of the door digging into his back. Aloysius scrambled to his feet first and pressed his advantage, directing a kick at Shepard's unprotected face with an armoured boot, the self-serving psychopath managing to fall aside from the blow and reducing the blow to a glancing impact that nonetheless had him seeing stars.

Before the terrorist could withdraw the limb, Shepard grabbed at it, held it against the wall with his left hand before punching behind the knee with his right, causing the joint to bend and the ambusher to lean further in towards his hunter, his balance even more compromised. Shepard managed to exploit his foe's plight by shoving the other human to the right into the open doorway, giving him a window to regain his own feet in order to pursue-

And find himself once more at a disadvantage when Charon lashed out with a vicious combo of kicks at various points on the assassin's body, stalling his advance before a parried blow of Shepard's own led to him receiving a brutal blow to the head, catching the exact area that had been caught mere moments ago by the nihilist's kick, allowing the older man to manoeuvre Thaddaeus back further and further towards the hazard lurking behind him in the form of the downward flight of steps.

Aware of his plight and the necessity to alter the momentum of the combat into his favour, restoring his control, Shepard attempted to ram a heavy blow into the terrorist's chest with the sole of his armoured boot. The attempt succeeded, however, understanding Shepard's motivations, rather than halting or even giving ground with the blow in order to limit the force delivered by the impact, instead applied Newton's third law to the situation; 'Every action has an equal and opposite reaction'-

And drove forwards into Shepard's foot, actually resulting in some bruising to his own torso, but in return causing Shepard to topple, off balance and surprised by the move, back down the steps. Aloysius made to follow-

But was forestalled by the impact of several rounds from the assassin's Karpov, somehow drawn during and aimed immediately after Thanatos' unfortunate encounter with gravity, bringing the terrorist's shields down to hazardously low levels and encouraging him to adopt the attitude that discretion was the better part of valour in this particular situation. So, instead of attacking further, Walker prudently took the alternative direction offered by the staircase and fled up it in great, leaping strides.

Shepard cursed aloud fervently as he got to his feet and made to follow, taking the stairs three at a time, his trenchcoat flaring out behind him, his eyes never leaving his prey, looking for an opportunity to open fire.

For Charon's part, not once did he make the amateurish mistake of looking behind him to ascertain the position of his pursuer, never stumbled, tripped or faltered, until he burst out into the wind and the chill air of the terminal roof. Looking at it conventionally, it appeared to be a dead end, leaving him trapped in a fight or die scenario.

Like Shepard, however, Walker knew that one could escape from just about anywhere without a fight with the proper and intelligent application of creative, unorthodox thinking.

And he'd trained himself in more than just running...

Shepard reached the door less than half a minute behind his quarry, but elected to risk losing more time and increasing the distance between them in favour of exercising greater caution; whilst it was possible that the nihilist would simply rely on Shepard's paranoia to buy him more time, it was also possible that he would rely on Shepard believing that that was the case and laying another ambush. There was little to no point considering further as it would give no conclusions without more data, and in any case the course of action to follow was the one that was least likely on average, taking into account most scenarios as well as their probability, to result in his premature death.

Shepard hacked the door's console and opened it from the side so as to be concealed from those watching the door as it opened, before stepping away from the open portal so that he'd have a greater distance between himself and any threats, sidearm raised as he moved out into the open-

To see the terrorist standing near the edge of the section of roof, perhaps ten metres away, his back to the man who hunted him.

Shepard fired.

Charon took a brief run-up and jumped, descended rapidly out of the assassin's line of sight and landing on the adjacent area of concrete, studded with ventilation outlets, rolling with the impact and rising to his feet before following a vector that offered the most efficient route to a different building.

Shepard followed without hesitation, sprinting to the edge of the roof and tracking his quarry with his weapon for half a second before concluding that he wouldn't be able to knock out the terrorist's shields before he made it out of range of the N7's sidearm, and mimicking his prey's earlier leap.

Karpov still in hand, he looked for a more efficient route in order to cut down on the distance between him and his target, opening fire as he did so in an effort to get the nihilist to slow down in trying to evade the projectiles, resulting in Walker simply veering so that a ventilation outlet blocked the assassin's line of sight, giving Shepard no choice other than to follow and keep looking for another course of action; at the moment the scenario was almost entirely in his foe's favour.

The gap to the next building was a long one; over five metres, which would have been manageable, had neither man been wearing armour or bearing weaponry. However, Walker made it with relative ease, vaulting a ventilation outlet to grant him a greater altitude from which to make the jump, grabbing onto the edge of the building and scrambling up quickly before swerving off on a tangent to his previous route to avoid the inevitable fire from his pursuer, who stalled, then was forced instead to attempt to replicate the feat without any experience in the field; Shepard's philosophy had been to improvise in such circumstances, as prescribing to a specific practice allowed one's opponents to predict one's reactions with greater ease. However, he couldn't spot an alternative, in this case, which seemed to indicate a flaw in the strategy.

He bore lighter armour than that chosen by Charon, and carried less in the way of weaponry, yet he also carried his sidearm in one hand, something that he was unwilling to change in the event that he got an opportunity to open fire on his foe or vice versa, and the trophy from Torfan whipped around him fiercely in the wind, distorting his profile which would be an asset were he the one being hunted, yet it also tugged at his balance and impeded his movements slightly.

Assessing the drop to be one that he would be unable to survive under almost any circumstances, and only too aware of the increasing distance between himself and his quarry, Shepard backed up again to afford himself the opportunity to increase his forward momentum, then sprinted straight at the same ventilation outlet, pushed himself off of the ground with his less favoured left leg, awkwardly landed on the raised (and not especially robust) surface, and launched himself into space with the same limb he landed on.

Karpov in his right hand, he reached for the edge of the building with his left, seeing that his jump had given him the approximate trajectory to hit the wall at a sufficient altitude to prevent himself from falling to his death, and though he could feel the high winds tugging at him and pulling him off course, it seemed that they wouldn't have sufficient effect-

He slammed into the edge of the wall at about chest height, the impact driving the breath from his lungs and bruising his torso painfully in spite of his armour, and immediately tried to gain sufficient traction with which to pull himself up.

Easier said than done; his hand gaining friction but no purchase as it scrabbled against the frustratingly smooth roof, his right having even less of an effect as it bore a weapon, and his legs and feet pressed themselves vainly against the side of the building, yet he was slipping, and his current actions were unlikely to alter that.

He swore aloud in spite of himself, pushed the pistol from himself in order to free his other hand without sacrificing the weapon permanently, and managed to halt his inexorable regress backwards.

He sighed with relief, and strained to pull himself up safely, managing to get his torso up over the edge, rotate himself and then roll to safety-

To see the terrorist standing over him, holding the assassin's own weapon, aimed unerringly between Shepard's eyes.

Certain death or almost certain death. Choices, choices...

Shepard snap-rolled back in the opposite direction, away from his enemy's muzzle flash that had actually been adjusted in anticipation of a move towards himself, and dropped into the void.