It was almost a relief when Grandad fell down. He'd seemed unstoppable, so full of billowing life, just months ago. Then Sophie had had to watch as the long limbs knotted with pain, the runner's lungs shrivelling to torn sacks rustling with papery breath. Watching him struggle through the rituals of existence was like watching a priceless antique clock with its winding mechanism tossed out suddenly and carelessly one day with the rubbish. Winding down until there was nothing left to move its treasured twitching hands. Stretching through the minutes against the inevitable.

And now the pendulum of his legs ceased mid-stride. The trunk above sighed and came loose from its proud disregard for gravity. He looked down at Charlotte almost in surprise, burbling beneath him in blissful ignorance of this parting of ways. The pendulum had stopped, but the upper workings had one last stretch, one last second to mark in defiance of the time they measured. A crease of concentration flickered briefly across his fear. Then he took hold of the pram with both gnarled claws and pushed it gently but firmly from his trajectory. Sophie loved him for that, and the pain of his love would last forever.

The sight of Grandad's baggy crumpled form on the pavement released all the agonised potential that his draining life force had filled. Sophie had seen this moment a million times in nightmares and in daydreams, on the dark canvas of her ceiling, for long, long weeks. Sometimes it was in his bed in the converted living room in the gentle light of morning. Sometimes in the park, a price paid for one more brisk stagger through the roads of his youth. But here it now was in real life, not in the mournful gold of dawn but a slightly drizzly autumn twilight, halfway down Moore Street on the way to Aunty Eileen's for fish and chips and a heap of famously undercooked apple crumble. And, as she looked down at the spot where her lifelong friend had inverted into brutal nothingness, all the tear-salted circuits of her memory fired the acid understanding that she must meet it with nothingness of her own.

Still, she knelt. And in rolling over the heap of anorak and bones she saw his lined face twitch and in that moment decision degraded to possibility.

She shook her mobile desperately from her pocket. Grandad's eyes flickered at the sound.

"Please..." said a voice no stronger than a summer breeze. "No... think... your daughter."

Sophie fumbled out the number from memory and pressed call. The voice she heard next could not be more different from the failing breath of the man below her. Cheery smiley chatter fell over the silence of helplessness. Custard over shit.

"Welcome to SmartAid. If you have not yet upgraded to one of our Gold Plus Emergency Care Packs, including-"

Sophie pressed hash and cut off the robot in the prime of its sugary monologue. Seconds cost lives. She'd learnt the trick a long time ago.

She entered the code quickly, before it had time to speak. Someone else was speaking too. The wet bubbling from Grandad surely did have words at its heart, but they were complete gibberish through the rattle of his throat. She understood the flapping at the pram though. One boneless arm crashed against the seat and rocked it momentarily onto two wheels. Charlotte began to wail.

"To upgrade to Varidol, our latest breakthrough in our range of-"

Hash. Number three. The voice squawked off, and a one hundred and twenty pound sterling drop of the substance that had been sealed into a small subdermal panel in Grandad's left biceps slid noiselessly into a nearby artery.

Grandad groaned, shuddered and lay still. Glassy eyes stared at darkness. A lump of meat, discarded on the flagstones and the slow decay was over at last and then the meat was thrashing and choking again, animation returned in a mockery of life.

Sophie recoiled and grasped at the phone that had fallen to the ground. She had to do something to block out the memory of the rush of guilty joy when he fell still, so she pressed three again.

Another violent flap, the last instinctive strain of a landed fish struggling for the water's edge inches from the bank. Then sentience returned to his stare and that was the worst of all.

"Sophie, please... Charlotte-" and the breath ended. She looked down at the body and saw only Grandad and the finger jabbed at the keypad again. And again. And again.

She looked around. The few people around had of course crossed the street and marched on, stealing embarrassed glances at the heap of clothes. But then someone was rounding the corner, and as Grandad lurched for her leg, Sophie staggered free and into the stranger's startled arms.

"Please, please, we need an ambulance! I'll - I'll pay you back, I'll find a way-"

Grandad was coughing out blood and chewed fragments of admonition. The man's frightened eyes shifted from the bedraggled woman and he pushed wordlessly on his way.

She didn't even turn. Hash and three. Hash and three. Five minutes later, the man was leaving the pizza shop a block up the street and the implant had run dry.

It had been panic, instinct, a base primal desire to help the unhelpable. She didn't know if she'd overdosed him in the end. She didn't know how many times she'd made the command. She couldn't meet his dulling eyes, or the baby's. Because it hadn't been her money to spend and Charlotte's university fund was gone.

She stood shivering by the pram for a moment more, and from some remote place common sense returned. She left him where he was and hurried onwards down the road. The sweepers would be there soon; no need to waste more on a funeral. She'd ignored him enough already.

Sophie hovered for a moment, shy and awkward and distraught as the stranger she'd practically assaulted finished his supper and wandered back to the electronics shop next door. What had she been thinking? He could report her for begging, and then Charlotte would have no mum as well as no future.

She'd ignored him. She'd ignored Grandad and failed her daughter, and she suddenly had the overwhelming conviction that she could not stomach Aunty Eileen's undercooked crumble tonight.

She didn't look back at the place the pendulum had stopped.

She'd tell Eileen tomorrow. After a rest. Too numb to think. She shuffled forward, raised a stiff arm, and opened the door with a traitor's hand.

Ham and pineapple would be nice.