I know what you've seen in the comics and on Smallville, Superman and Supergirl are cousins.  Well, apparently they are kissing cousins behind the scenes and they've got the little piece of kryptonite to prove it.

If I were Supergirl I'd keep an eye on ol' Red there.  I know it's called the fortress of solitude but I'm guessing Superman could fit one more in there. 

Photo: Just Jared