The hardest part of two Pisces together is that nobody is left to hold the map. Both of you drift, both of you avoid the hard conversation by changing the subject to a feeling instead of a fact, and both of you will say "we should talk about the money situation" for three months running without ever picking a date to do it. Mutable signs flow easily together, which sounds lovely until you realize flowing means nobody is steering. You can end up two years into a relationship with no savings plan, no clear sense of who pays what bill, and a vague, warm agreement that things will "sort themselves out." They often don't.
But sit with what this pairing gets right, because it is rare. There is no translating required. When one of you comes home wrung out and quiet, the other doesn't ask what's wrong, they just lower the lights and put on the right music, because they already know. Neptune rules you both, and Neptune doesn't deal in small talk, it deals in the unspoken thing underneath. You'll finish each other's sentences about a dream you had, cry at the same films, build a private language of half-jokes and old songs that outsiders find slightly mysterious.
The risk isn't conflict, it's dissolving into each other and losing the outline of where one of you ends and the other begins. You'll need one person, on any given week, to be the one who books the appointment, answers the email, says the unromantic true thing out loud. Take turns at it. Otherwise the same soft blind spot swallows you both.