Power. That's what you two will generate when you're together, and just like electricity itself, you'll have to be extremely careful as to how you direct it. The energy, passion, and, yes, anger you'll inspire in each other could consume you if you aren't careful.
It will help if you and your friend are both emotionally stable people, because this connection may bring out your dark side. You'll tap into your friend's natural energy, and they'll tap into your own deepest source of power, but in a way that could create conflict. There's a dangerous, risk-taking quality to your particular union. If anger overtakes you, you'll find it really difficult to stay rational. Let's hope you're both levelheaded enough to talk out your feelings calmly rather than engaging in psychological warfare. If you aren't careful, this relationship could degenerate into little more than an ongoing power struggle. But if you can find ways to tone down the aggression and talk things out, you'll transform yourselves and the way that you approach conflict.