'A little bit off' was a fair assessment. Grantaire had seen Enjolras' report about the flag, and with the giant painting still in his living room he hadn't actually worked up the nerve to destroy it like he claimed to want to, the whole situation struck him badly. He'd been moping around his apartment, drinking casually and sketching various things from memory since before all the Wonderland weirdness started. His dreams had imparted a great deal of artistic training (much to the shock of his professors), even if those memories were hazy from booze. He practiced when he was frequently bored.
However, after Enjolras' flag appearing in real life, Grantaire had started getting more serious with his alcohol, letting his artistic pursuits fall to the wayside.
When Sif contacted him, at first he wasn't going to respond. But she sounded emotional, so Grantaire thought he should at least hear her out.
At the knock at his door, Grantaire looked up from where he was dozing in his chair. When he stood, two sketchbooks (one new and one two centuries old) fell to the floor off his lap. He ignored them. It took him a minute to stumble to the door and straighten himself up enough for company, running a hand though his messy hair. It wasn't perfect, but it would have to do.
Grantaire's front door was still a little warped from being broken into, and he had to pull a little harder than normal to open it. "Ah, Sif, you made it. Come in."