Re: re-inventing myself
I suppose you can use any planet for anything, it's still a part of who you are.
12th house can also be art, the movies, meditation and healing. The being in a water house would mean there are emotional undercurrents surrounding it. You might be very touchy when it comes to that planet.
I read somewhere (I think it was in 'The Luminaries: The Psychology of the Sun and the Moon in the Horoscope' by Liz Green & Howard Sasportas, but I'm not sure) that the 12th house can also show unconscious family patterns. Like a certain scenario you play in your family not being fully aware of it and it's passed from generation to generation in very sutble ways you can't put your finger to. Gestures, things not said, subtle frowning when you don't follow the ritual.
Also the 12th house might not be very visible for you but it's very visible to the people around you as it is above the horizon. They instictively sense your 12th house features even if you yourself are not fully aware of them. And if there are planets in the 12th house you might even shove them in people's faces much more often than you imagine until at some point they go 'hey, enough of your ego (Sun)/ preaching (Jupiter)/ aggression (Mars),' etc. And you go, what ego, what preaching, what aggression, what are you talking about? And you honestly don't see what people have been noticing about you all along. There might have been a subtle family pattern of 'I-am-the-best' (Sun), 'you should always fight for what you want' (Mars), 'I'm always right and I'll teach you how to live' (Jupiter) which is not always clearly vocalised and yet available upon closer analysis.
At the same time in the same book I think it says that the cadent houses show the skills you can use in society and in your profession especially since they allow you to adapt their energy to the wants and needs of the environment. I personally have Jupiter in domicile in Pisces in the 12th house and have been working as a teacher for the past five years. And I've often been accused of a know-it-all attitude outside of my job of which I am not fully aware but at least am a little more willing to admit. There was a certain pattern of 'I'm right and you're wrong' by default in my family too as well as certain escapism, fondness for certain substances and accepting the position of a victim (12th house cusp Pisces). This becomes something like a family model which is passed on. Also both my grandparents on my father's side worked as teachers.
I think that the first step is to recognise those patterns and those energies in us as much as we can and then we can use them more or less consciously. Although on the other hand you have the principle of sublimation and if you believe in it, the more I become aware of my own pompousness, let's say, the less likely I will be continue teaching.
As far as the ruler of the 12th making a nice aspect to the ruler of the 10th, in my chart they form a nice square with a 2-degree orb, the other planet involved being Saturn. Maybe Saturn is able to curb some of that pompousness and also make Jupiter take his aggrandized statements more seriously and make it more down-to-earth. Also the square is a very good propelling aspect although not the most pleasant on the inside of course. In the case of Saturn it causes a lot of self-doubt which on the other hand leads to the willingness for constant improvement.
I recently read the opinion that drug addiction and mental disorders are caused my trines not squares. Trines make people lazy and expecting too much for free. Squares make people work their hands to the bone and never be happy with the results.