Conversation Piece

Kylo Ren keeps the charred skull of Darth Vader in his quarters, along with (so we're assured by the internet) the ashes of his victims.

Yeah, not creepy at all. Everyone keeps the skull of their genocidal grandpa on the dining room table. You, know for puppet shows and stuff.

Ren uses it as his Linus Security Blanket to renew his commitment to the dark side every time he starts questioning the program:

REN: Forgive me. I feel it again. The pull to the light. Supreme Leader senses it. Show me again the power of the darkness, and I will let nothing stand in our way. Show me, Grandfather, and I will finish what you started.

The obvious allusion is to Yorick's skull, the most famous stage prop in the whole wide world, which Hamlet uses to meditate on life and death.

Ren is taking the same concept and applying it to the Force: using the skull to see the power of the dark side and remind him why he wears a mask and Force-chokes anyone who doesn't bring him his morning Danish promptly at 9 a.m. (And that Danish better be warm, too. Warm and gooey.)

It's also a reminder of his family's legacy, and the fact that it entails a fair amount of the dark side as well as the light. Anakin fell to his own anger and need for control. Luke passed the test that Anakin failed.

Now there's Ben, who's clearly still fighting the same battle that they did and is trying to convince himself that Team Evil really is the way to go. That battle is in his blood, and the skull serves as a constant reminder of what the stakes are…for him and for the whole galaxy.