Enjolras returns the look. Directness is his natural state. "I do."

If it were one of the others, no more words would be needed. But then, if it were one of the others, the question would never have been asked.

"I don't understand the joke you see. But I do believe you. And I've always known you to be capable."

Capable, and loyal -- there has never been doubt of Grantaire betraying them. It's only a question of whether he would ever feel motivated to turn his skills to any serious purpose. But here, after death, in a bar filled with the impossible, it seems he's found that motivation.