Bioshock Infinite: Rosalind and Robert Lutece. The same coin, a different perspective. Rosalind, a quantum physicist, spent years searching for the existence of other realities. One day she accidently found her double Robert in a neighbouring universe. Identical except for the sex chromosome, she passed him off as her twin when he crossed over into her world. The two are always together - hilariously finishing each others sentences in Colombia. "But I am with my brother, and so I am content....