[quote=@tipssyCalibrator]Also, what do you mean by "Accelerator"?[/quote]

I think they're talking about a character from A Certain Magical Index.

I'm strongly leaning towards Jonathan getting his lessons from a combination of Alexei and whoever the substitute teacher or alternative teacher is, though, so it's not necessary to get a new mentor specifically for him. No problems with the current cast -- I can make it work. :D