I expected it to be more difficult.

It was a solid plan, don't get me wrong, but I really thought it would need several upgrades and refinements before it worked. I was expecting that the first time would mostly be an inconvenience for him - for someone so famed for last-minute, death-defying escapes - and a learning experience for me. I thought I'd spend months, years, tinkering with the formula, finding better and more subtle ways to hide traps, before I finally brought him down.

But no! First time, total victory. I guess it's easy to get complacent when no one you normally grapple with is taking it seriously either. I guess it's easy to spend as little time on your own safety as you do thinking about collataral damage when you - genuinely - believe you're the 'next step of evolution'.

Total cost to me: $32.80, including shipping. Most of that went to high-tension braided fishing wire, the rest to the various screws and fixings I needed to hang it. $32.80's not a high price to pay to kill a demigod, especially not compared to the cost I'd paid so far for his continued existence.

I set it all up myself; it's easier to keep a secret between only one person, and most people - somehow - still think of heroes as a net benefit. I waited until night fell, and then snuck out to string my wire across the alleyway.

It's not a well-trafficked alley. The streets on either side are nicer to walk along, and - given the state of the concrete and the broken bottles - it's actually less efficient to cut through it than to go round. The only reason you'd ever really take it in a hurry would be if you were the sort of person who prided themselves on always taking the most efficient route between any two points - no matter what or who was in your way - and you happened to be in exactly the right place at the right time.

I've watched a thousand videos of him a thousand times. He was really very predictable: stimulus led immediately to response. No matter what else was going on, if he heard the right trigger sound - maniacal laughter, the tread of a killbot, the whine of a recharging laser - he was off in a split second.

He tookk the simplest possible route between point A and point B that doesn't involve literally going through a wall, every time. Super-speed, not invulnerability, you see. So an alley he happened to be walking past at that exact moment? You knew he'd head down it. Likewise a plateglass window, a hot dog stand, a woman doing her shopping: if he was quick enough and it was small enough to shoulder aside or charge through, he went for it.

So what if the window breaks? So what if she falls, and hits her head? He's off saving the city, chasing down some mutant doctor with plans to briefly kidnap the mayor. So what if insurance won't pay out, or she dies on a street corner because the emergency services don't interfere in 'hero activity'? So what if people lose everything while he's posing for action shots with his opponent?

I stood at one end of the alley. Only a few yards - not that he would remember - from where it all happened. I shouted, with as much theatricality as I could muster, the name of his 'nemesis'. They belong to the same golf club.

At the other end of the alley, he heard me. Abandoned his date outside the same cheap restaurant he took them all to. Took off like lightning, like a cheetah, like someone so much faster than a normal person he'd forgotten that they still mattered. The wire took him in the throat.

It was anti-climactic. As I said, no death-defying escape, no snappy one-liner. It didn't kill him, but it stopped him dead, and pain wasn't something he'd ever had to get used to. He just lay there, wheezing, hands clutched to his throat, but he didn't do anything to help himself. Pathetic.

She'd not had his advantages. Smaller, weaker - 'mundane', they call it. But she fought in a way he didn't - held her shattered skull together, crawled towards help that arrived two hours too late. 'Heroic' is the word they use to describe him.

I wasn't sure what to do. Remember, I hadn't really expected this to work - this was a fact-finding mission, nothing more. But as he lay there, sobbing for air, it seemed foolish not to take advantage of the opportunity.

A brick, in the end. Not a ray gun, or a force blast, or a super-powered punch. Not, I imagine, the way he planned to go, if he was even capable of contemplating meaningful defeat. Her name was the last word he heard, though I'm not sure how many of the wet, heavy thuds he remained conscious for.

Obviously they caught me - we wouldn't be talking otherwise. With their tech, and their psychics, escape was never on the cards. I didn't put up a fight, though it occurred to me, given how easily he'd gone down, that I might have made a decent go of one. But no - the system's rotten, for sure, but my personal grievance is done. Let others, when they realise how tarnished those shiny supers are, take up the fight.

I'm content to sit here. To spend most of my time in solitary, as I've done ever since she died. To ignore the constant requests from reporters for interviews, the endless speculation as to motive. Was I brainwashed? Am I a new model of killbot, indistinguishable from a human? Perhaps a secret, forgotten supervillain? I don't care if they speculate, assign me a name, a costume, imagined elaborate crimes and a rivalry stretching back decades. It doesn't matter.

People tell you - it's a cliché at this point - that revenge isn't worth it. That it doesn't fill the emptiness, that the pain doesn't fade. I'm sure that's true. But what I did there - in that dark alley with a bloodstained brick - was at least as much justice as revenge, and justice, let me tell you, is a balm for the soul.