Fullmetal Alchemist: Brotherhood

[Jessper]

Was Marcoh one to begin with?

Oh that might have been me making things up, I guess I thought that because father kept him alive.

there are four alchemists who have opened the gate. Alphonse and Ed, Izumi, and, of course, Hoenheim.

We only ever saw Hoenheim witness the gate being opened, he didn't actually do it himself, right? Though that might be good enough.