<p>So consider this, what if there where a character (most likely a villain) who's mother underwent vanishing twin syndrome when they were in the womb. Vanishing Twin Syndrom or (VTS) is when a miscarriage occurs during pregnancy & one twin's tissue is absorbed by the other. For instance what if this character's mother was a Waterbender who married a Firebender. Maybe some situation like her father disapproved of her marrying a non-waterbender so he attacked her with bloodbending causing a miscarriage/VTS. We know siblings can have different bending in situations of mixed marriages. And we know in the situation of twins one can be a bender & one may not be so its not too far of a stretch to assume a set of twins could have different bending too. What if one twin was a waterbender & the other a firebender but one absorbed the other creating the only non-avatar duo-bender, one eye hazel one eye blue. Since spirits are a thing this character could probably see his twin, who's physical bending abilities he borrows, like an imaginary friend making him seem mentally deranged. People would probably think him the Avatar initially. What do you guys think? </p>