Can somebody explain this? I understand the dude in the first row is a badass called Mountain, and the lady in the second row is some kind of fierce dragon bitch, but I’m at a loss on the third one.
Since I am too cheap to pay for HBO and I found the GoT books unreadable, I’m keeping up with via episode reviews, spoilers, and whatever memes come across my Facebook feed. So far it’s pretty epic.
That’s Lady Mormont, basically a badass despite being 10 years old. She shows up old dudes with regularity by being a staunch supporter of House Stark when the old dudes find excuses to not honor their promises. So the meme is basically “Cersei has this big badass warrior, Daenerys has dragons, but Jon Snow has Lady Mormont, who is tougher and scarier than anything else.”
Whoa. I did not see that coming.
The following two scenes might help you understand why she was an instant success:
I think that clip is better characterized as Davos tells Lady Mormont what’s what!
As someone who doesn’t watch GoT either, but sees the memes and Facebook threads anyway…I can’t tell you how much I love how you’re expressing this. 
Or rather, he is telling everyone what’s what: The time for games is over, the dead are coming, and the living must unite to not join them. I still wonder why the one line of reasoning that swayed Miss Mormont was abandoned by Jon and Sansa when they met the other Houses.
For some perspective: Lady Mormont was NOT a major character until this most recent episode. She became an overnight fan favorite and the newest breakout character thanks to this one scene (which which she completely shames and humiliates a room full of grown-ass men).