Aberforth to provide back Story

[Alz]

Prediction: Aberforth will provide 'backstory' on Dumbledore
I it my belief and prediction that Aberforth will come to Harry or Harry will seek him out, and Dumbledore's past will be told to Harry.

Evidence or Support
This is of course as a result of JKR tipping but I think Dumbledore told Aberforth that in the case of his demise he was to hunt Harry out and give him certain details - details he didnt want Harry to know unless he told him himself or should be shared when he died so Harry would know.
I would go as far as to say that Aberforth might even be holding certain information that should be given to Harry on Dumbledore's death.

[halliemei]

Like Alz, I think that JKR has pointed us to DD's history. Who else knows his history but his brother? Members of the Order know bits and pieces, but not the whole thing, and we remember from the Memerson interview that JRK said that we'll learn more (part 2):

JKR: It’s possible, it's possible that you will know that. You will — [pause] — you will know more about Dumbledore. I have to be sooo careful on this.

And, in part one:

ES: I know Dumbledore likes to see the good in people but he seems trusting almost to the point of recklessness sometimes.

[Laughter] Yes, I would agree. I would agree.

ES: How can someone so -

JKR: Intelligent -

ES: be so blind with regard to certain things?

JKR: Well, there is information on that to come, in seven. But I would say that I think it has been demonstrated, particularly in books five and six that immense brainpower does not protect you from emotional mistakes and I think Dumbledore really exemplifies that. In fact, I would tend to think that being very, very intelligent might create some problems and it has done for Dumbledore, because his wisdom has isolated him, and I think you can see that in the books, because where is his equal, where is his confidante, where is his partner? He has none of those things. He’s always the one who gives, he’s always the one who has the insight and has the knowledge. So I think that, while I ask the reader to accept that McGonagall is a very worthy second in command, she is not an equal. You have a slightly circuitous answer, but I can't get much closer than that.

ES: No, that was a good answer.

MA: It's interesting about Dumbledore being lonely.

JKR: I see him as isolated, and a few people have said to me rightly I think, that he is detached. My sister said to me in a moment of frustration, it was when Hagrid was shut up in his house after Rita Skeeter had published that he was a half-breed, and my sister said to me, “Why didn't Dumbledore go down earlier, why didn't Dumbledore go down earlier?” I said he really had to let Hagrid stew for a while and see if he was going to come out of this on his own because if he had come out on his own he really would have been better. "Well he's too detached, he's too cold, it's like you,” she said!" [Laughter] By which she meant that where she would immediately rush in and I would maybe stand back a little bit and say, “Let's wait and see if he can work this out.” I wouldn't leave him a week. I'd leave him maybe an afternoon. But she would chase him into the hut.

No one is his equal. No one knows. UNLESS of course DD was married and we never knew -- and she didn't come to the funeral. Yeah, right.

[Lovegood54]

dumbledore may have been married, but i dont think he was (after all, most people would keep a picture of their wife on their desk if they were away from home for months at a time, and dumbledore doesnt appear to have one does he?) and given the number of people who attended his funeral (harry sees "hundreds of chairs" set up when he goes to where the funeral is being held) and also, he didnt recognize most of the people when he arrived, and only half the chairs were filled at that point, so if he did have a wife, it would be very easy for her to not be noticed by harry. but i would say if he ever was married, his wife would have died many years ago (possibly at the hand of Grindelwald, could explain his reaction to the potion when retrieving the horcrux and the murder of a loved one usually makes people seek to avenge the departed) anyway, since JKR says we are going to learn more about Dumbledor ein book seven, i see the information coming from Aberforth and those who are in the Order.

[Fortescue]

Well, I agreed, but not to the wording. I don't think there is anything ominous about Dumbledore. Not that way at least. I believe Aberforth will reveal a lot to Harry, and maybe much of it will be things that, to this point, Dumbledore had kept from him. I think the grumpy old bartender that smells of goats will be quite informative to Harry in the final book.