Two water signs read each other without words: intuition, emotional memory, an intimacy few bonds reach. You also catch each other's moods dangerously easily. Your work: don't drown together — someone has to remember to open the window.
One initiates (cardinal), the other sustains (fixed): done well, it's the formula for projects that start AND finish. Done badly, one pushes change and the other digs in. Negotiation is this bond's muscle.