shrug
Both will be wanting to get ahead against tough negotiators, but the tail can not wag the dog. A modest increase in spending in NI perhaps on a valid project or so that might have been on the back burner otherwise; is a reasonable outcome for the DUP to say, "Look at what we got for NI". If they are trying to live up to their reputation as tough negotiators and holding out for more, then it's unlikely to be forthcoming. It is unlikely that, generally speaking, they will want to vote against the government anyway; and if they did, after a few of those another GE would be called and the public would have to decide whether to vote for another hung parliament or give the one that seems to want to get a decent Brexit deal a better shot at it; having given them (or maybe just the PM) a bloody nose last time. (Unless, of course, the country has a "Road to Damascus" type revelation and votes UKIP in.)