I've always loved the 666 batsuit. it's my fav batsuit ever. It's unique, dramatic, it has a collar inspired by Discowing and it's based on his batboy batsuit that is precious and significant.
The batboy suit was a secret which means that young Damian since he was banned from playing dress up with his then unknown dad's suit spent time thinking and designing his own.
I can just imagine Damian aged younger than 10 with a secret sketch book fantasising of a dad he never met but clearly admired and being just like him.
I wonder how many designs he ditched before he landed on that one