Lovers? Christ, no!

That idea has never occured to me, and even thinking about it now I just can't see it...

As for being related? Likewise, they just seem to be too different.

My suggestion (and it is only speculation) is that the two new each other from a very early age, but rather than growing the same they complimented each other...

I think that they've probably been playing, training and fighting together since long before joining Seifer.

I like the idea that perhaps they met each other when they were young (perhaps before being adopted) and so they might have been given the names that compliment each other by whoever adopted them...

Still, in all honesty I think there's far too little information to draw any conclusions at all...