dragon roars: 100000 damage
jzargo dies
*types resurrect in console*
jzargo comes back to life

have u done that? That cat is one of the best followers, so dont make him die!@

Opens console... and *poof* J'zargo is back from the dead.

Other than the one follower whom I sacrificed to the quest, everyone else who followed me died to various traps they stepped on.

Dirge in Skyrim is probably not good at either of those skills.

Then there's that Orc in the DB in Cheydinhal, who doesn't bother with stealth. Therris could be more thuggish than other members of the thieves' guild. Not all thieves have the same skills. There's pickpockets, lockpickers, cat-burglars, con artists, etc, not to mention Therris could sneak around and pick locks if he took an invisibility potion.

Therris doesn't appear to be anything like them two in The Real Barenziah, his personality and ways just tell of him being a usual thief. Not any exception to the rule.

Although this is my opinion on the subject. His personality to me just says 'suthay-raht thief khajiit' and I'm happy to agree to disagree.
Even to the extent of going against Douglas Goodall's word on the subject.

Probably xD He's pretty BAMFy like that; he doesn't give a damn if a Kamehameha is in the way.