Without knowing his background, you'll obviously never know for sure, but if I was to hazard a guess, looking at him I would say he is a cross between a Netherland Dwarf and a Rex (or mini Rex). In the photos of him as a baby he is distinctively Nethie looking, very rounded with fairly little ears. In the older pictures he is a typical Rex shape in his head and body, and his coat looks quite Rex-like too, dense and plush looking. He's also got the ears, whilst most non standard nethies tend to have slightly longer ears, their not that big!! Rex's on the other hand do have long big ears, longer than yours has as the dwarf in him will have played a part in that, but their still typically Rex like. His colour by the way is black otter, a very popular and common colour in both Rex's and Nethies which is why you've seen so many neth's that look like him
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