Lil Pump was the original NPC who you selected your faction from. However, he is now currently removed from Vesteria. To select a Faction, you must now go to the faction base and talk to the faction leader.
His existence is reflected through William Pumpernickle in Nilgarf, an NPC that shares his appearance and stature. His new name may have been a reference to Albert's (Flamingo) video on Vesteria during Alpha, where he said: "It shouldn't be Lil' Pump, it should be something medieval, like 'Lilliam Pumpernickle'". Thus, he became William Pumpernickle when he was no longer used to choose factions.
While you can not interact with this character as of now; he will ask the player who they are before ending the conversation. It is unknown if he will be more useful later.