"Merely a scholar."
coming… later >_>
Riyaz is mild-mannered and almost excessively polite; however, he never defers to others and any attempts at bossing him around or forcing him into something he doesn't want to do will result in a politely steely refusal. On matters he considers trivial, however, he's actually very obliging and is usually willing to step forward and lend a hand if asked, so the fact that he actually has a spine can come as a surprise.
Part of the reason he's so obliging is his own curiosity. Riyaz is highly observant, and he likes gathering information for future reference. There's also a genuine side to it, however; he will step forward to help someone who's truly in need if it comes at no cost to his motives. It takes a serious personal investment for him to cross his own agenda, however.
He doesn't like to talk about himself, and tends to deflect questions about his past or his motives despite being relatively open about his home world - this last is because, in Nautilus, he is aware that no one there can ever use the information he gives them against Tetherius. In general, he is distrustful by nature, and keeps his secrets closely.
Riyaz is psychic; more specifically, he is a clairvoyant, able to see things taking place at the same time in other locations. He cannot see into the future or past. He is also able to sense Rift quakes, as all psychics can, and has the relatively unusual ability of crossing the Rift at will, or Travelling. In Nautilus, he has managed to regain his clairvoyance but can't yet see things with any great detail. Also, as the Rift does not exist in the city, his ability to sense it and his Travelling ability are virtually useless.
Riyaz is also something of an amateur linguist, fluent in many tongues and dialects from around the multiverse.
Monday: Probably the closest friend he has in Nautilus. Riyaz gets along with Monday quite well and almost trusts him. He's grateful to the Denizen for introducing him to Bending and is intrigued by his abilities and background.
Aya Brea: She tried to set him on fire, but he doesn't hold it against her. Rather, he feels slightly responsible for being unable to stop her. He'd be quick to help her if she needed it. In general, he feels she's a reliable person.
Eve Brea: He's genuinely sorry about what she had to go through, and feels a little protective of her.
Tony Stark: is a terrible influence. Riyaz is really fascinated by the things Tony's done with Bending, which has made him want to start applying it in more advanced ways.
Chisato Madison: They have a lot in common, both of them investigating and taking note of everything that goes on. As such, he's taken a liking to her, and is impressed by her information-gathering skills. When Chisato was killed, Riyaz was devastated, something that truly surprised him. He was forced to reevaluate his priorities and his passive manner, and resolved that in the future he would never again stand by and allow something like this to happen without taking action.
Ratchet: helped him cope in the time between Chisato's death and the attack on Isis, and helped him learn how to do something useful by teaching him medical Bending. He's truly grateful for that, and has a genuine respect for the old bot.
Lelouch: He got to know him during their planning for the City of Glass attack, and was truly impressed by his strategic thinking.
(more coming, probably)