Lady Lena really wants me to app the Janitor from Scrubs, so he can stalk and torture JD. I'm still undecided, though.
If I keep apping characters until I've taken one from every significant Megaten game, then Chiaki from Nocturne, Gouto from Raidou Kuzunoha (he's a talking cat!), and Gale from DDS. Other contenders would be Simon Tam from Firefly (he's such a derpy dork, it'd be so much fun) and definitely someone from Durarara!! -- possibly Kasuka or Mikado.
Pair off my kids with whoever in Marina you think is best! (Including Ryoji, if you wish.)