Oddly enough, I can picture Sera and Vivienne getting along in a catty sort of way. Viv is in a special situation where she has power within a system that usually shuns people like her. I could see Sera begrudgingly respecting that in time. It depends on what their arcs are, I guess.
I found the wording used to describe how Vivienne views Cole interesting. Why "banish safely" and not simply destroy/eliminate? The former could indicate that she understands the danger of interacting with spirits, while not necessarily viewing Cole as malevolent. Basically, just wanting him away from mortals who would otherwise corrupt him, intentionally or not. Also notice that by comparison with Sera, who's described as "refusing to talk to 'it' altogether" it would seem she does at least acknowledge his existence if you let him join; though I suspect she'd keep things very short and aloof with him (for both their sakes).
Wait... so Dorian makes fun of Sera in that party? I thought they were both on team YOLO?
This is all very confusing... *has flashbacks to high school*
Good be good natured ribbing from his end; that Sera will heartily return when he least expects it.