The former Lions duo are among the smallest centres in the game but D'Arcy reckons they punch above their weight due to fiercely competitive attitudes.
"Brian's been great to play with for all these years," said D'Arcy.
"We've been in and around teams together since we were 16 or 17.
"We've always played together and he's so easy to play with, whether it's in attack or defence.
"One of the things that stands out for both of us is that we enjoy tackling and the confrontation.
"We have the chip on our shoulder that you need to be a really good defender. That was epitomised last Saturday when Brian stopped one of Wales' second rows dead in his tracks five metres from our line.
"When you see stuff like that it's inspiring in it's own right. A mantra in this squad is 'no matter what it takes to get it done, just do it'.
"That's come across in the way Brian and I have played down the years."
Ireland are set to have their hands full once again with England, who have opted to stick with Brad Barritt and Billy Twelvetrees.
The clash in Dublin will be pivotal to the outcome of the Championship and D'Arcy is well aware of the threat posed by the Red Rose.
"Brian and I love defending and love challenges. We've always been up against really good players over the years and we've always held our own.
"I watched all of England's matches in November and when you do that you think about how you would defend at certain moments.
"My mates won't watch games with me because I look at it half analytically and they say 'great, you've sucked the fun out of a good weekend!'.
"England were very impressive. They were up for it, the 50-50 balls which are things that New Zealand usually dominate England controlled."