Agent Arthur Bell is an Elite Boss who works for Longbow.
The Ballista are Longbow's heaviest hitters. These tankers are tough enough to withstand direct hits from rocket launchers, and can dish out enough damage to take out the toughest brute Arachnos can throw at them.
During the mission End Longbow's investigation. Permanently he says the following:
Before combat: What I can't figure out is Villain's part in all this. Is it money, or mind control?
Combat starts: I should have figured I'd see more of Uqua's pets.
At 75% Life: Why are we fighting? Don't you know what Uqua is?
At 50% Life: You stupid idiot! The world must know, for all our sakes!
At 25% Life: Files Transferring... Gotta hold out...just a bit longer...
Defeated: Gotta warn... Uqua is... Uqua is... is a... Ri...
Defeating player: Stay down! Just let me get the data out!