Personally, my most extensive interaction with SLEs is with my younger brother. The sibling duality is unique on it's own because you can definitely identify that quadra spirit outright - that's basically the link that ties us together. It's more like a hot-blooded sense of mo'fo' spirit, really; rage against the stolid, outmoded, and senselessly conformist machine of society that our parents try so desperately to indoctrinate us into.
There's a shared sense of rebellion between the us of us. My brother's mode of rebellion, though, is much more explicit than mine. He's the one that will tend to curse out my parents when things get rough. I'll usually just keep that anger (there's spite in me yet and I have no idea where it comes from - it just seems like the inherent result of everything that is wrong with this world, eating at me like a scalding poker in the gut) within, and then release it through conversation with my brother (he can, of course, sympathize and share in the rage), or more often than not, through something like music. Both of us have pretty edgy interests - punk-rock integrity in all our music (hell, opera is scary shit), violent contact sports, and can't stand television shows without a biting satirical or sadistic slant.
In romantic relationships, I've only had one with a confirmed ESTp. There, too, we shared anger against pretty much everyone and everything, but it was slightly less apparent without a parental figure to really rise up against. Of course, we didn't spend our entire time together commisserating and brooding and the like. We had fun! In fact, I think we just tried to make each other laugh more often than not. Whether it was to counteract the negativity we both felt to the percieved oppression or just to assert our own vitality, I don't really know. That girl was funny, though. She thought of everything I didn't, and I lent an understanding ear and myself as punching bag.