Pluto also means intensity, compulsion, one-pointed determination, wilfulness. I assume it's in Virgo? This is the sign of the server, the duty manager, the one who works meticulously behind the scenes to make sure all details are correct so that something can be achieved. The combination of Pisces and Virgo can make a dedicated worker for a cause. Does that fit at all?
When you have an opposition like that, Pluto can also be 'met' in other people. They will try to dominate the Pisces person who will give way. After too much of giving way, eventually the Pisces Sun will learn to empower themselves and not be pushed around or over-subservient to others.
It would look a harder placement for a woman than a man because she'll meet a reflection of the Sun-Pluto opposition in her father and then husband or significant males in her life.
