Some other forums have some forms of tags that might be useful here.
The first one, the spoiler one is a little box which contains a spoiler. The person that wishes to see the spoiler can click on it, while the person that doesn't could just ignore it.
The second one, the hidden tag allows people to write text that is going to be hidden from view until the person replies to the thread. Let's say I write some text and add an "hidden" part, well you couldn't see that part until YOU replied to the thread. There is still some sort of box saying that there is hidden text.
There, I'm just throwing new ideas you might like to make this forum even better than it is.