Franziska von Karma: This is his biological daughter, as well as his student. He has taken her for granted throughout her life, instead focusing on his elder student (and enemy) Miles Edgeworth for the purposes of revenge against him. Deep down, he cares about Franziska but has difficulty expressing affection towards her, believing that doing so would compel her to become too soft and thus lose her drive to carry on the von Karma legacy of perfection.
At the moment (right before the planned room search, that is), he is quite unhappy with his daughter, not so much because she is trying to investigate him for the "alleged" incident on NS 35, but rather that she is showing disrespect towards him and is slipping out of his control. Welcome to the wonderful world of parenting unruly teenagers, Papa! XD I will update this after the end of NS 43, as the room search and fingerprinting will likely change his opinion of her.
Miles Edgeworth: It goes without saying, but von Karma wants to utterly destroy this pathetic son-of-an-Edgeworth. XD There are no words that can adequately describe the level of hatred he bears for his former student.
Detective Dick Gumshoe: A miserable waste of taxpayer's dollars. von Karma dislikes this bumbling detective a lot, especially since he is so sickeningly loyal towards Edgeworth. However, so long as this oaf stays out of von Karma's way, he's safe from the brunt of the elder prosecutor's wrath.
Phoenix Wright: The pesky defense attorney who has never learned to mind his own business, thus ruining the elder prosecutor's life and career. von Karma wants to make sure that this spiky-haired wretch joins his student in hell, once he sends him there.
Luxord: The prosecutor only spoke to Luxord once, upon his arrival at Landel's. Because he was new to the experience, he believed the man was insane and unstable. By now, he has forgotten about him, although his opinion of him would likely be different were the two to meet again.
Mousse (dropped): von Karma only spoke to Mousse once, during his first day at Landel's. The boy seemed to show promise at first, as it appeared that von Karma could get useful information -- or even a weapon -- from him. But then Mousse smothered him in emotion, which repulsed the prosecutor. By now, von Karma has already forgotten about him.
Javert: At first, von Karma respected (even almost liked) his first roommate. Though the man told of the same bizarre stories that the others had, at least he showed a degree of rationality and level-headedness of which the prosecutor approved. The information Mr. Javert gave von Karma proved sound -- and infinitely useful to him -- so it was he who von Karma first sought out when he reawakened at the Institute after a nearly week-long coma.
However... now von Karma has a suspicion that Javert may have betrayed him. He doesn't know for sure, but some deductions he made based on some things Franziska said to him have led him to suspect that Javert is the "neutral, disinterested party" who had given her tips on the NS 35 incident. Until he can confirm this for certain, he will maintain a high guard around this man at all times.
Lelouch Lamperouge: The prosecutor has only seen this man's posts on the bulletin board, but he already respects him for the highly useful and well-organized information he has posted to it.
Megatron: von Karma hasn't gotten to speak to his new roommate very much yet, but at the moment, he's fairly neutral towards him, though rather disapproving due to the man's inclination to sleep a great deal.
Scar: At the moment, von Karma still distrusts Scar, but after the events of NS 42, he grudgingly admits that the man's word is generally sound. Plus, he has provided useful information to him. So, while the prosecutor is still reluctant to consider Mr. Scar as a truly potential ally just yet, he definitely bears no ill will towards him.
Yomi: Right now, von Karma is fairly neutral towards this young woman, whom he first met in the file room during NS 41 and later spoke to in the Library during DS 43. However, as with most of the other patients, he doesn't really trust her.
Kristoph: von Karma has only met his canonmate once, during the bus ride to Doyleton, and they hadn't even learned each other's names. However, the smarmy man has already managed to irritate the prosecutor, so von Karma definitely distrusts him. However, there is potential for a grudging alliance between the two, as von Karma learns more about Kristoph in time; the perfect bargaining chip would be the information Kristoph has about Edgeworth.
Ryuk (dropped ;_; ): Ryuk has definitely managed to piss off von Karma, after literally twisting his arm to force him to procure an apple for him. XD There is something about the man's childish, overly familiar manner that reminds the prosecutor of someone from his past who also deliberately irritated him just for the fun of it. Still, there is also something intriguing about the fact that Ryuk -- a virtual stranger -- knows who he is upon sight.
Sergeant Taura: At the moment, Ms. Taura is the only one whom von Karma can consider an ally at the Institute (barring his daughter). She is respectful towards him, shows regard for his needs without drawing attention to it or otherwise being overtly condescending about it, is very intelligent, and appears to have the potential as a highly capable fighter (this will be confirmed once he actually sees her do so).
Adachi (dropped): von Karma has only met Adachi once but already feels that he is untrustworthy, due to the odd conversation between him and Ms. Callisto at the Twin Pine Restaurant.
Callisto: As with Mr. Adachi, von Karma distrusts Ms. Callisto at this time, due to the conversation between her and Mr. Adachi at the Twin Pine Restaurant.
Inspector Lunge: Another man whom von Karma doesn't know in person yet, but whom he respects for the meticulous attention to detail on the bulletin board.
Mr. Spock: von Karma doesn't know the pointy-eared bastard the Vulcan, but he already likes him. XD (Well, about as much as von Karma can really like anyone whom he has yet to meet in person, that is. XD ) This is due to the man's impressively perfect handwriting and the intelligent questions he has posed on the board.
Homura: von Karma only really knows that this man is the head of the History Club; there have been conflicting attitudes expressed towards him on the bulletin board. Ms. Taura seems to think positively towards him, but until von Karma can meet this man, he will mainly glean information about him through the young woman.