I also wanted to know more about this fella, from what I gather (googling the net) he was part of the thunder warriors a group of super soldiers created by the emperor to unite terra.
they were successful and took over Terra quickly but that was the point, the emperor created them to be big brutish powerful fighters and that's all, no smarts just brawns.
So accepting his fate Arik escaped and has been conducting his own experiments...
that's as far as my data goes anyone want to enlighten me more please do tell.
I like too think
GW is keeping Arik as an excuse to create another human faction, led by him and his new Thunder Warriors.......
Or at least a forge world army....

my fav version of the armor (Even before I knew about thunder warriors)