Mr_Ruse said: Yeah, at this point I wouldn't be surprised if Rose and Roxy get shanked by Bec Noir in a single strike.
Funny you should mention that. At least one Jack has an established repoir with Karkat. Imagine if that one arrived first. :/ The other Jacks might need to pause for a moment, too, to figure out how to handle alternate selves.
Honestly I see Union Jack as the biggest problem to worry about. Bec Noir's the second most dangerous/powerful outright, but he's got PM on his tail to keep him balanced in the long run. Spades Slick isn't even really evil as much as a ne'er-do-well, and the biggest problem he presents is bringing the whole Felt with him.