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I think that Kennen and Gragas are actually both in the counter-initiation camp/follow up category as well. Kennen's stun takes a little while to hit and it's somewhat easy to see coming and kite away from. Ideally he follows someone like Malphite or Amumu in and gets his ult on everybody.
Honestly, if you want to play an AP mid with strong initiation, just follow ReginaId from Team Solomid. His self-described role is to start fights that Chaox (their AD Carry) can win. He plays a lot of TF (Twisted Fate) and Morgana. TF is also great because he can initiate almost anywhere on the map. If you like starting fights, I'd start there.