Replying...
Intro. Yo, it's the freaking demon-killer-guy, Doomguy. He kinda hates Hell a little bit, for reasons. But he kinda chill when he ain't angry beyond what Samuel Hayden can comprehend. Anyways, for those that don't know, I THINK the reson why he hates Hell so much is because they slaughtered his wife and children, plus his bunny. I know the bunny one is true, not sure about the wife and kid part (I dislike DOOM Eternal's gameplay, I haven't beat it yet so I wouldn't know much). I know this is the DOOM 2016 depiction, but you still kinda need lore from DOOM Eternal to fugure out what the hell is going on. Anyways, the freaky 3 metre science man Samuel Hayden decided it would be fun to yoink the Crucible from Doomguy and then walk off to restart the UAC. I hope the AI is intelligent enough to piece together that the Crucible got yoinked. If not, let's just say this is an alt timeline where Hayden died before he could yoink the Crucible.

Doom Slayer (DOOM 2016)

@sleag