After a quick tour of a hell dimension, a portal opens somewhere in a less crowded part the bar and Montparnasse steps through.
Slowly, weakly, he leans against a wall. Laughing, quietly but maniacally, he gazes about the bar, eyes somewhat vacant. Something has changed and it's not just his seemingly good mood. Still laughing rather chillingly, he slides to the floor. When he finds himself sitting, leaning against the wall, he puts his head in his hands. He keeps his knees pulled in close to his chest. Only then does he stop laughing.
He runs his hands through his hair, tugging on it rather fiercely. Primarily to give himself something to focus on to keep from drifting away again, and partially because he feels the desire to cause pain. For someone. Anyone. In the meantime, he's willing to settle for himself. He draws one of his knives with his good hand and tests the blade against his arm, reassuring himself of its sharpness.
A thin rivulet of blood appears and trickles down the inside of his forearm. Pleased by this, he grins wickedly and watches the light glint off the blade and the bloody slowly drip next to him. The cut is not very deep but will continue to bleed for sometime if not treated.
So, there is a rather less sane Montparnasse in an empty corner of the bar. Because this bar does have oh-so-many corners. Come find out what happened, investigate the source of the laughter, or at least get the knives away from him before he leaves a larger red puddle on the floor. Just be careful that it is not your own.