Aw, c'mon George.
A guess is not the same as a spoiler.
It's only a spoiler if you KNOW ahead of time it's true.
Totally 100% disagree.
One of the most breathtaking reveals I have ever seen, was in Doctor Who's S6 E7 episode "When a Good Man goes to War". In it we find out who River Song is.
** MIND BLOWING** "Holy Crap!!!" moment.
Equal to Luke finding out who his father was, and in Babylon-5 finding out who Valen was.
It would have been TOTALLY RUINED if have seen a "pre-emptive Spoiler" guess by anyone who guessed that. It would not have been the mind-blowing shock that it was.
So, nope, I'm not going to be a pre-emptive spoiler.
BTW- Doctor Who SPOILER alert, for those who have not seen it but might watch Doctor Who some day, avoid this.
Here is a reaction video of that episode. Watch the reaction at 9:20, near the end of the episode. Of course it would more sense if a person watched the show. Alex Kingston is River Song, who randomly appears in several episodes over the years (two episodes with a different Doctor), and they have a timey-wimey relationship (first episode she appears in, she is older than in this episode as she has her own time and space travel gadget, and tells the Doctor she has known him for years. They meet up in different timelines back-and-forth). The two others (Amy Pond and Rory) are the Doctor's regular companions.
Watch for River to appear for the shock at about 9:20 in the video. Although for the full context I highly recommend seeing the whole thing (it will explain the leaf-thing better, and a massive plot point before the reveal). Oh, if you do see it, at some point she was in a prison, but frequently
sneaks out and then comes back as in the early part of this episode. In any case, the reaction you see in this video, was pretty much my reaction when I saw it.