With Pluto in the 1st House, your life purpose is to assert yourself and discover yourself. There is a tendency to be particularly dominating, asserting, perhaps "squashing" other people before they have the time to squash you. Do note, I'm using these words with intent - Pluto is about power, control and domination, and when Pluto is in the 1st house, there is a tendency to perceive most situations as a win/lose situation, victim/victor, and so there is a tendency to placate people, especially of course in situations of conflict or perceived conflict, to make sure you remain in control, on top, winning.
There can be a sense of cyclic identity crisis with this position, and the push and pull in relationships can be very strong too. With Pluto, we're always in a dynamic of dominance or submission, and with Pluto in this 1st House, it's not likely that you'll be submissive. Ultimately, you're learning to be empowered without being controlling, you're learning how to be dominant without being a bully, and you're learning how to be assertive without being aggressive.
Pluto energy is about becoming friend with your personal demons, acknowledging their presence, and having the conscious awareness that you are capable of the worst. Yet, true power comes from this awareness, and making the conscious choice not to indulge, making the conscious choice to remain in your highest self and energy. When you have Pluto in the 1st house, you should be particularly aware of this dynamic, particularly aware of your personal demons and particularly aware of the choice to make.
It's likely that a lot of your relationships will be based on power struggle. There is with this position of Pluto a difficulty with equality, a tendency to feel safe only when in a position of dominance. Power struggles occur because Pluto is particularly afraid of losing power and being controlled. Can't be controlled if you make sure you're always the one doing it right? The key here is to become aware of it, consciously allow yourself to be vulnerable, let other people the chance to hurt you, or control you, relying on the knowledge that if it comes to it, you are largely powerful enough to extricate yourself from the situation and regenerate yourself.
Personal readings available
"Pluto an evolutionary journey of the soul": By Jeff Green
"The book of Pluto": Steven Forrest