Rudol von Stroheim

Rudol von Stroheim is a bonus boss found in the Harbor. He can also be spoken to with Joseph to alter later events of the story.

Events
Stroheim first appears in the Harbor, where he can be battled as an optional boss. If defeated, he disappears from the rest of the story. Alternatively, Joseph can talk to him for a short event, which changes some later story events.

If Stroheim is spoken to in the Harbor, Speedwagon will later appear in Calcutta. If both of them are spoken to in their respective areas, they will become the player's escorts if they follow Polnareff and get shot by Hol Horse.

Stroheim makes a short cameo in the submarine, where he leaves the group a note and several items. If he wasn't defeated in the Harbor, this is the only way to obtain the Ultraviolet Lasers.

If Stroheim was spoken to in the Harbor, Speedwagon was spoken to in Calcutta, the ruins in Aswan were explored with Dire, and Joseph has more FP than any other party member, Stroheim will make a final appearance during the final battle with Dio, where he blasts Dio with his ultraviolet lasers to disrupt The World's time stop.

Extra Content
On the 10th playthrough and up, you can battle Stroheim by talking to him in the Developer's Room. Since you can't use the radio to equip or change tactics in the Dev Room, you'll have to do so before fighting Vins (or before entering the mansion on the Succession End).