Heh, his and his father's names were taken from the names of constellations, Draco the Dragon and Scorpius the Scorpion. I guess it was a continuation of the Black family tradition of naming children after stars/constellations (Sirius, Regulus, Bellatrix, Andromeda...) There are other constellation names I would've preferred to Scorpius. :o) On the other hand, with a name like Scorpius, the gryffindor kids can tease him.."Nanner, Nanner, Scorpius, the Porpious" or maybe, "Scorpius, the dorkius" if they want, too. Yes, I know it's spelled Porpoise..
hehehe! Knowing the British habit of shortening and adding diminutives to names, I'd expect him to wind up with the nickname "Skorpy". I guess that's still better than the nickname Aberforth used for Mundungus Fletcher, though! ;)