At the way to work, I've been thinking about Death (the Discworld character, not the actual thing) and the rules it follows. I remembered a scene which makes him look like an obvious antagonist.
In the Colour of Magic, Twoflower explains concept of insurance to the owner of the Broken Drum, Broadman:
"Tavern fights are pretty common around here, I expect?"
"No doubt fixtures and fittings get damaged?"
"Fixt - oh, I see. You mean like benches and whatnot. Yes, I suppose so."
"That must be upsetting for the innkeepers."
"I’ve never really thought about it. I suppose it must be one of the risks of the job."
Twoflower regarded him thoughtfully.
"I might be able to help there." he said. "Risks are my business."
However all the owner understood was that “If my property gets damaged, I will receive money” as seen later on:
Down in the cellar Broadman looked up, muttered to himself, and carried on with his work. His entire spindlewinter's supply of candles had already been strewn on the floor, mixed with his store of kindling wood. Now he was attacking a barrel of lamp oil. "inn-sewer-ants" he muttered. Oil gushed out and swirled around his feet
He did not manage to set his property ablaze all by himself though - his tinderbox was damp. Which is what my question is about:
A lighted taper appeared in mid-air, right beside him.
Hᴇʀᴇ, ᴛᴀᴋᴇ ᴛʜɪs.
"Thanks," said Broadman.
Dᴏɴ'ᴛ ᴍᴇɴᴛɪᴏɴ ɪᴛ.
The Discworld wiki discards Death's role completely:
The Great Fire Of Ankh-Morpork was caused by Broadman the owner of the Broken Drum, when he tried to burn down the bulding
Is there any (in universe) explanation what Death's motives were here? I mean he clearly knew what is about to happen. Out of universe, it allowed for awesome dramatic scene of course:
Broadman went to throw the taper down the steps. His hand paused in mid-air. He looked at the taper, his brow furrowing. Then he turned around and held the taper up to illuminate the scene. It didn't shed much light, but it did give the darkness a shape...
"Oh, no" he breathed.
Bᴜᴛ ʏᴇs, said Death.
The closure of the scene also almost implies it wasn't Broadman who threw the torch.