I haven't read any of the other comments, to not be influenced, so I don't know how others have done this. But I've done it as a short story.

Nigel woke to another sunny day. He stretched and yawned, and for a moment, one blessed moment, he was happy. But then he remembered and the pain came crashing down again.

It was six months since his wife and daughter had been killed by the drunk driver and the pain hadn’t lessened at all.

Some days he was numb. Some days he felt the depths of despair. Some days the anger was overwhelming. But most days it was searing pain and crippling grief.

He was still unable to comprehend why the driver only got community service and six months loss of licence, while Nigel had lost his whole reason for living.

He’d stopped going into work, and didn’t care when he was sacked. His savings would run out soon, but he couldn’t bring himself to care about that either.

He wasn’t sure when he had started stalking Chester. It must be a few weeks ago, as he knew Chester’s routine by heart.

He now frequently dropped into Chester’s favourite bar. Often enough that they now acknowledged each other with the kind of nod you give someone you see around but don’t actually know.

Nigel didn’t know why he did this, but remembered the old adage – keep your friends close, and your enemies closer.

That night, as Nigel approached the bar – on foot, he didn’t drive any more – he saw a car he recognised, Chester’s. He must have his licence back.

Nigel’s already fragile state of mind shattered. He looked wildly around, and saw an empty bottle in the gutter. He grabbed it and smashed it against Chester’s windscreen in a fury. When the bottle broke in his hand, he looked down at the shard of glass he was now holding, and the blood on his hand, and finally knew what he had to do. He must stop Chester from killing again.

Ignoring the pain in his hand, he resolutely turned towards the bar.

EDIT - posted here https://steemit.com/fiction/@kiwideb/flash-fiction-son-of-satire-s-empathy-competition, and this post resteemed.