Nero knows very little about his past if anything at all . He could only recall small and breif memories about his family and clan and that they were supposedly greatly feared. He recalls small glimps of his mothers face but also glimps of relentless torture on him and his mother. These horrible memories haunts his dreams and thoughts continueously never giving him rest.
Nevertheless, Nero is and has always been a level headed and calm indivdual. His kekki genkai has been control over an odd, immense, and mostly unstable energy that has been passed down through the members of his clan that he now assums to have long ago died out. Another of his rather easier abilities (kekki genkai abilty)are black portal like gateways that he is able to create with little to no chakra consumption with a mere desire of wanting them to appear allowing him to pass through them and appear out wherever he so desires. He is also able to determine there size but only to a very limited extent(5,7 to the size of a fist)
Nero has been claimed to be an advanced strategist and skilled fighter but that of course was in his past which is unfortunatly lost to him by some unfortunate events. He has now stumbled across the village hidden in the depths where he hopes to call home..