Barricade was Soundwave's number one lieutenant on Cybertron. As part of the Decepticon Secret Police, many ordinary bots who didn't wish to choose sides suddenly were very willing to join Megatron's crusade or ended up being found at the bottom of a smelting pit after an unfortunate "accident" at his hands. He doesn't condone deserters or traitors and executes his tasks with a mixture of stealth and brutal efficiency. 

If Barricade had a human face, he'd always be scowling. I don't think this is a character that's ever been in a good mood. He's no-nonsense, all business, all the time. There's no suave coolness to the character like Keith David's performance for the 2007 PS2/Nintendo DS game would have you believe. Barricade is a Decepticon you do not want to mess with, and a low register voice will get that across very well. No other qualifications, so have fun experimenting and pretending to rough up some Autobots.