RWBY - Family Issues

The only man edgy enough.

No, it's obviously Reaper. After Mercy performed voodoo shit on Gabriel's corpse after the blast, fragments of him were scattered throughout the multiverse and manifested itself in different ways. For some fucking reason, one of those fragments landed in Remnant and manifested itself as a Faunus which later became Adam's father.

And that's how Mercy lost her medical license.