I think there might be a hint to Art liking Scarlet when they are in the waste compactor at the Quentin labs. When he notices how she had been speaking in unison with the other quadruplets, he seems worried and asks if she is still her normal self. When she replies "I'm not you. I'm Scarlet." he seems relieved that she is still her normal (if a bit ditzy) self. I haven't noticed Scarlet exhibiting any interest in Art though.
I think there is also some hint that there may be something between Art and Kat as well, however, nothing in particular comes to mind. There does seem to be some mutual "like" between the two. It's possible that they like each other but feel like they are in the other's "friend zone" and so don't want to risk ruining their good friendship by trying to take it farther.
It's also possible that any imagined relationship between any of the characters is just wishful thinking by us viewers who are either romantic or want to just see some art of the couples together, or some combiantion of the two, and that JJ intends to keep the relationships purely platonic.
I think that Art might have come off as interested in Kat a bit (as can be seen in his image of her fantasy character in a chrome thong), but I can't recall any interest of Kat in Art. She may have flirted with him a bit, but it might have been in more a joking manner.
I for one though can't stand unrequited love and unresolved relation tensions, so I do hope JJ includes an arc that resolves some of the characters feelings and relationship intents towards each other.
As for Pip, I think he deserves a second chance at Fern.