Thank you for this lovely comment! :) Despite their shortcomings, as you say, Marcus and Theo ARE Slytherins, and ambition can make up for a lot. :) Dudley is one of my very favorite characters, and the little glimpse of redemption JK gave us in canon was just enough to make him a very fun character to write post war.
Snape... LOL. No, maybe not mellowed but perhaps a bit less ruthless (only because he knows Harry wouldn't approve of anything too drastic) *g*. And to hear that you liked my Snape and my Harry as well is very happy making. *beams*