You may fight him as Johnny in a flashback but that outcome is predetermined as per the lore (Johnny gets buttraeped). Therefore there is absolutely no doubt that you will fight him again as a player near the endgame; with Johnny egging you on inside your stupid brain. He will likely have Johnny's gf as a hostage and you have to save her.
This game will revolve around fulfilling Johnny's agenda's. The only free agency you as a player will have will be driving around like a retard and shooting people in the street until the flying cops come and kill you, just like GTAs.
Enjoy your RPG of the Year morons. The
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crowd will be playing Wrath of the Righteous, & Solasta instead. (and mayyybe BG III if it massively improves the writing over DoS series)