Samur Maykr

Samur Maykr is the only known Seraphim in Doom Eternal. Samur was responsible for empowering the Doom Slayer, and for stealing the "The Father " from Urdak. Samur's current whereabouts are unknown.

Speculation
Samur was able to use the Maykr machine in Hell, despite being a Maykr being, therefore unable to traverse Hell. It is possible that the flashback with Samur Maykr takes place in the same building, in a different plane (before it was moved to the facility in Hell).