Old but gold!

 

I mean, he gave it to him after Christmas so that he could complain about Snape, then didn't remind him about it when he broke into Umbridge's office to use the Floo to speak to him...but that's probably being needlessly pedantic, isn't it?

 

Let's not look for nuance where there isn't any. Repeat after me: bad plotting. JK forgot about the mirror until the chapter where Harry goes back to his dorm and then decided rather than rewriting the whole book to make sense she just wrote that both Harry and Sirius forgot about this means of communication that she went out of her way to introduce.

 

...rewrite the whole book for what, exactly? All she would have to do to was to remove the line with the mirror. Anyway, Harry didn't know it was a mirror until after Sirius's death. He refused to even open the wrapper on the thing.

As for Sirius, he would probably have been proud that Harry chose the fireplace and not the mirror. After all, the risk would have been what made it fun for James.

 

I actually don't think it's particularly bad plotting. It's a mix of human error and stubbornness helping cause something tragic. It's heavy handed, but nothing wrong with it apart from that.

 

http://memesbams.com/harry-potter-memes/

 

I liked it much better without the Dumbledore bit.

 

...

The theory is that Dumbledore represents death from the Three Brothers, as Voldemort, Snape and Harry represent each brother, not that Dumbledore is literally death.

 

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EDIT2: