What do I do with Tales of Terror?

They have a number of uses. For one, 77 are needed (along with many other items) to write the "Book of the Zee" victory condition. Another is that after you return to London 3(?) times you can access a tattoo parlour. There various items can be consumed as the inspiration of a stat boosting tattoo (Tale of Terror is iron+2). Not sure if you can visit the parlour later... I tend to make many long trips instead of constantly heading back to London. Finally, you can trade with them in Whithers (follow the coast north from London to Vender... then just keep following it as the snow starts) You can buy fuel/supplies with them (1 for 1).

If there are any other uses... Idon't know either.

To clarify, Zee Stories buy fuel and tales of terror buy supplies in Whither.

Also, there is another possibility of using both (Zee story+tale of terror) when exploring Mutton Island beach (random chance of event happening, without them y ou gain a terror story, lose some echos, and gain 5 terror).