Rahjaak is a Rakshasa Prince/Swordsage/Spy/Sorcerer/Bodyguard/Assassin recently summoned and bound to House Illafin's service through a Summon Planar Ally spell cast by Lady Lar'wae. Unlike most of his kind, he prefers martial mastery over manipulation however, and sees an alliance with Drow to be helpful to his long term goals of overthrowing the Rakshasa Maharaja back home. For mature audiences he also finds Drow women to be particularly attractive (and before anyone suggests it let me say that I myself am NOT a furry IRL...).
Also unlike most Rakshasa, Rahjaak finds assuming "lesser" forms distasteful so unless specifically ordered to he would rather not take on an infiltration role. Still for the purposes of misdirection he likely takes the form of another race such as an Illithid or a Tren when out in public...the better to maintain the upper hand in any sort of conflict where knowing his true race would pose a risk (i.e people who know about Rakshasa's are less likely to waste actions casting spells at them...).