Chapter 35 of Dimensional Links is up and titled "This Is My Time-Loop Detector, It Goes Ding When There's Stuff" On AO3 | On FF.net
And for the interested, a snippet:
“...Is he not here?” Steam wondered, glancing around with mostly-disguised curiosity.
“No, he's here,” Mask sighed. “But he probably wants to-”
A soft, amused chuckle sounded right in his ear and Mask only avoided startling because this had happened to him several times before. The rest of the group wasn't so lucky. Several of them flinched, Sketch actually managed to clear a full three inches, and Tetra, in a move that Mask was starting to suspect was a reflex of hers, tried to shoot the Salesman in the face. Emphasis on tried - she missed, because the man suddenly and simply wasn't there anymore.
“-be dramatic,” Mask finished, resignedly. “Hello sir, pardon our intrusion.”
The Happy Mask Salesman (now suddenly there in a completely different part of the Tower) was comically thin in comparison to the backpack he carried, which was at minimum three times wider than he was and stuffed to the seams. His hair was red and rigidly fixed into place, his eyes were creased shut in a facsimile of cheerfulness, and his mouth was stretched into an unmoving, bulletproof smile.
He gave off the impression that he might go for the throat if anything happened to break his friendly customer-service mask.