Hey again

This hand was weird even from the beginning. Pretty rare to see someone open raising for 6bb, so my plan was to 3bet lighter and play IP as an aggressor. I would probably fold to a shove.

Decent flop..so decided to cbet for value/protection. I used a bit bigger sizing since I am not interested in range betting given it is multiway and the board connects with their calling ranges pretty naturally. My sizing was 1/2 pot so I have some reasonably amount left for shoving the turn. However, not in this case:/
Pretty strong line from him - could have even AA,KK in his range. However, I would be more concerned if the first player would have shoved since he still do have one player behind. So the villain has probably more bluffs since now we are heads up.
Okay here are my data points why I decided to call.
He opened for 6bb preflop - even if he is unknown it actually indicates some kind of volatility
We have at least some split equity with AK.
It is a decent assumption that he is slowplaying KK+ especially after 6bb open.
The volatility makes me wonder (whether) he might raise KQ for value.. or flush draws as a bluff

Thoughts? :)