Rupert was many things; unintelligent, unreliable, untrustworthy, lazy and unfashionable, but most of all he was a stupid coward. He was scared of the little things in life that most people grew out of, scared of unrealistic scenarios that would never happen to him. For example, his ultimate fear would be to be kidnapped by aliens and taken to be re-programmed on board their ship; and yet he would happily climb down a manhole and confront a dangerous man who was potentially armed. Rupert was also terrified of spiders. He was in need of a severe change of perspective, although his stupidity which may come across as bravery, makes him a perfect candidate for confrontational scenes in his line of work.
All of these details tell you exactly why he chose not to do the right thing here and tell the police about Tyler. His ideal fantasy was of his swooping in from a rope to the manhole lair, grabbing Tyler and shoving him in the back of a taxi while proving that Lance was innocent. Of course, that would never happen, as he had terrible hand-eye coordination, and so would fall off the rope or forget to grab Tyler. He was also banned from using the taxi service and wasn't very good at arguing so couldn't prove Lance's innocence. Apart from those minor details, this fantasy formed the basis of a thoroughly well thought out plan.
Rupert was in his apartment, and it was nearing sun down. There was a darkness hanging over Breckand Estate like an unwanted curtain and he could only vaguely see the park though the dim light of the burning anomalies. He strode up and down the living room, debating in his mind what to bring with him on his mission to identify Tyler as the killer. While he was doing this, he stroked his chin as he had seen in the movies and waited for the lightbulb moment which always followed. It didn't. In his dismayed state, he grabbed a torch, a kitkat, a kitchen knife and some rope and headed down to the manhole cover where he hoped Tyler would be.
It was raining and the persisting drizzle had defeated the flaming anomaly in the park, so the light was dismal as he jogged to the street of the lair. He fell over 3 rocks and walked a broken lampost before he thought to turn on the torch. The switch was a bit stiff as he never really needed it until this moment. Rupert struggled with the torch until he finally managed to move it. A flame flickered out of the 'bulb' and Rupert flung it into the air as he realised with a shock that this was the very 'torch' that had started all of the chaos in the first place. In amongst the havoc, he managed to drop the torch on the floor and the flame went abruptly out in the dampness. He sunk to his knees and groped around aimlessly for his only light source, but to no avail. The lighter was lost in the darkness.
Rupert continued on towards the manhole, holding onto the waist high walls of nearby houses as he went. It was the late evening now and light was diminishing even more rapidly. The streetlights were all disfunctional, after the council had decided to introduce greener movement sensitive triggers onto their lamposts. Obviously, these were a complete and utter failure. At last he found the manhole. He removed the cover, and stared down into the bleak unknown.
"The things I do for money", he commented to no-one in particular before realising with a grim dissatisfaction that he wasn't being paid for this at all.
He climbed a way down the ladder before replacing the cover on top of him. All shreds of light were now completely blocked and he was alone in the gloom. Well, not for long. He reached the bottom of the ladder and walked towards the faint humming and beeping he could hear. The tunnels were getting lighter now and Rupert could see shadows lurking ominously around every corner. At last, he could see a figure in the faint illuminations of the computer screens.
"Tyler." stated Rupert into the black. The figure turned around and stared at him, eyeing up his every movement, of which there weren't many. Rupert was frozen to the spot, almost too scared to move. Sweat collected under the hairline of his forehead and his fists were clenched, not with anger, mainly with cold. The figure stopped looking up and down Rupert and began to walk slowly towards him. He was wearing a balaclava this time and Rupert wondered why. He then realised that Tyler had a blood circularity disorder which prevented normal blood flow around his body in chilly times. He must be wearing it to warm him up.
The figure walked toward Rupert more quickly now, with some urgency this time. He stopped about 2 metres before Rupert. It was impossible to tell what he was feeling because of the balaclava but Rupert guessed he was nervous but the way he kept itching his covered nose. Slowly, he took off the balaclava.
"Aaaarrrrrrrgggghhhhhhhhh" screamed Rupert as he fainted onto the floor in shock.