Eh, aside from Luka, I can see Nic with Tim, Sylvia or Maria too!
Unless you guys want Maria to be the canon "doesn't S-Support quickly with anyone" because of lore (just like Lon'qu), of course...XD
As for Sylvia, I can see a fast S-Rank being one of:
It can't be Tim because Sylvia is carnivorous and
his opposite, not Natsume because Natsume is the silver-tongued manipulative sort, and not Nim because of history reasons. Not sure which is the most fitting, though? XD