Energetic, oblivious, and childish. Ask it what its favourite thing out of any category is ( colour, song, season ) and it’ll say “all of them”. 1347 doesn’t understand that it is very dangerous towards others. 

1347’s voice should be loud and bouncy, and possibly have a sort of growl to it. 1347’s voice could sound gender neutral. 

I’ve always imagined 1347 having a british accent, but to be fair, the year 1347 was when the Black Death arrived in Italy. So... British, Italian, whatever. A posh english accent should work though.