First off: Welcome TRMK community.
Secondly, drat. Voting for Dairou has ended, not that I would have made a difference, but I did want to post the reasons as to why I'd favor his induction in future MK games.
To me, he exemplifies the whole "chaos/order" and the trials that raise up from this duality much more than Hotaru and Havik, because unlike these guys he doesn't share the same zeal as these guys. He was groomed to enforce Order and defend Chaos but his own have turned on him after one mistake due to his own grief, disregarding all of his probable good deeds.
The experience would have probably left him bitter and apathetic, best analogy I can come up with to describe Dairou would be the anti-scorpion, whereas one relentlessly tracks thoses responsible for the death of his kin, I can see the other living the rest of his life living in exile in Outworld in some inn of ill repute living off as much of bounty hunting as petty crime. I actually came up with more stuff to add to Dairou's story and moveset but I realize that it's not the place, maybe I'll post something in the fan fiction sub-board (is that how it's called).
So anyway, who we talking 'bout again? Ah right, Darrius... Well, he's not the most original character under the sun, but one could raise the argument about Noob Saibot being just a palette swap in his first appearance. I really like the idea of Cage's coming to Seido rising questions about Orderrealm's less than free living conditions and adopting his sunglasses as a symbol of revolt. It would also be nice seeing Cage returning to Seido and react to somebody like Darrius (who's not a nice guy by any stretch) using his image to incite violent revolts.
But I'll have to say no about him returning in MKX, unless the whole of Seido has part in the plot.