Fans Point Out Obscure Albus Dumbledore Lore

From Redditoru/xboxg4mer:

Harry Potter's wand measures 11 inches. It is made of holly and has a phoenix feather core. Mr. Garrick Ollivander described this wand as an odd mix of core and wood. Fawkes, Albus Dumbledore's phoenix, gave the feather. Fawkes also donated another feather, which now sits in Lord Voldemort's wand.

From a formerRedditor:

Filming the sixth film, directors and writers gave Rowling a script. Dumbledore made a comment about a girl he dated. Rowling sent the script back with a note: "he’s gay." They removed the scene.

From Redditoru/HoldingDoors:

Dumbledore and Grindelwald quickly became best friends. Both were incredibly talented.

I do not know if Grindelwald ever loved Dumbledore. I assume Dumbledore loved him at some point. This caused Dumbledore to ignore Grindelwald's cruel side.

Grindelwald learned Arianna was an obscurial. This caused a fight between Grindelwald and Abeforth, as he protected his sister more. Albus joined to protect his brother. Arianna died in the end. Dumbledore felt heartbroken losing his best friend, love, and sister. This created hostility between him and his brother.

From Redditoru/MichelleRosie:

Dumbledore was about 115 years old, if my memory serves. JKR first stated 150, but they later found the math wrong.

From Redditoru/W1nn1ng101:

Dumbledore only overturned house cup rulings for Gryffindor. He also awarded points for breaking those rules.

From a formerRedditor:

Albus means white in Latin.

From Redditoru/nb75685:

Dumbledore has a scar above his knee. It looks like a map of the London Underground.

From Redditoru/chillhelm:

Dumbledore accidentally created a Horcrux in the form of his sister Ariana's Obscurius, which now resides in Credence Barebone. Grindelwald needs Credence to kill Albus of his own will, or else the Horcrux would keep Dumbledore alive.

Read the full theoryhere.