The following post lists characters that have had an impact on Matt in some way. If your character simply met and spoke with him one or two times, chances are they might not be listed here. Otherwise it would simply become a mess to keep track of.
those to keep close
"Sen" (
tostepforward)
(a.k.a. Yamazaki Ayumu) Pretending to be a scared prostitute the first night they met, Ayu has constantly kept Matt wondering about her true motives. She plays the seductress well enough, however, and at this point she pretty much has the man wrapped around her little finger. As far as he's concerned, the two are a couple.
Himura Kenshin (
degozaruyo)
Matt met Kenshin through the History Club, and managed to convince him to teach him some combat basics, though the man prefers not to teach and has tried to dump him on others. He's unaware of how much Ayu despises him. If anything, he sees the man as someone he can run to when in trouble, since he's the rescuing sort.
Homura (
screwthegods)
With the loss of Mello, Homura has taken over as Matt's current "boss" of sorts. He doesn't exactly care for the man, but if he does his job he might just find himself a little safer at Landel's, and he can deal with that.
those to keep an eye on
Miles Edgeworth (
high_prosecutor)
Matt's new roommate. He finds it lucky that he's been put with the man who makes the frequent newbie posts on the bulletin. Having seen him meet with Lelouch, he has even more reason to keep tabs even if not specifically given the task to.
Schuldig (
k4t4str0ph4l)
A telepath. He broke Mello's wrist and the blond seemed genuinely afraid of him. ...Did I mention he's a telepath? Right.
"Bob" (
bored_todeath)
(a.k.a. Ryuk) Having messed with the shinigami both on the bulletin and in person, Matt believes he may have an idea of exactly what this man really is, if not who specifically...
Lelouch (
kingside)
(a.k.a. Lelouch vi Britannia, Lelouch Lamperouge, Zero) An interesting individual who has recently taken to gathering information on the bulletin. Matt was assigned to keep tabs on Lelouch by Homura and has since succeeded in at least making himself look harmless to the teen.
Kururugi Suzaku (
superdynamic)
A young man with a... close connection to Lelouch. Matt met him while following the two of them around the Institute one night. As he seems to be from his target's home world, he may need to keep tabs on them both.
those to remember
dropped characters
Mello (cnfltofintrst) - Mello doesn't really need any explanation. He was there to tell Matt what had happened and to instruct him through the first few days in Landel's, but has recently disappeared.
Near (atoyboxworld) - Another someone with no explanation needed. It can't be said that Matt was upset to learn he'd vanished as well.
L (el_lolly_eat) - Matt met the man in person for the first time in the Institute, though he seemed to have been going through some troubling times before his disappearance. (to be moved soon with information on the new L, most likely)
Yagami Light (godhood) - Kira. Definitely someone to keep an eye on up until he vanished...
B (bthebest) - Formerly of Whammy's. Matt saw him speaking with Mello but never had a chance to talk with him himself.
Sagara Sanosuke (damnrudecock) - A friend of Kenshin's. Usually, when he had an assignment with them they both came along.