Is Barbatos Nightbringer? I could never finish the story so this doubt has remained with me; I don’t know if it’s ever explicitly stated, but you mentioned Barbatos being the father of demons, which in-game is a title given to nightbringer, along with the fact that he preceded the devildom altogether.
If so, why would he make us go into the past and why would he act oblivious, knowing it could cause severe consequences to the timeline and could get us stuck there?
1. Is Barbatos Nightbringer?
I don’t think something needs to be said in words for it to be obvious that something is the case.
It’s spelled out for us in every way except for words.
The trailer for game implied it, nightbringer talks to solomon exactly like Barbatos does, Barbatos has said to have never been a child and Nightbringer is the father of demons, Barbatos is said to have been stronger than previous demon kings, Barbatos and NightBringer both have the ability over time and Barbatos immediately knew MC was from the future and in some dialogue options covered for their mistake.
Also the game would not have logically created an entirely new character Nightbringer that we never see or hear from. If NightBringer were someone else it would have been stated that he was but it’s not.
I believe it’s 100% canon that Barbatos and NightBringer are the same person but some might disagree because it’s not said in words.
2. Why would he make us go to the past and act oblivious knowing it could have severe consequences?
Because the timeline would be completely different if MC hadn’t gone to the past. MC is responsible for the brothers coming to terms with their demonic selves, for Satan’s obsession with cats, for Levi’s love of anime, and many other things that directly affect the future including Diavolo becoming the person he is in the present timeline. They also rescued Lucifer and his brothers from imprisonment in Cocytus.
Solomon is also responsible for a few major things including Mammon’s gambling habit.
Them being sent to the past directly affects/creates the present timeline.
Barbatos acts oblivious because he doesn’t want to be confronted about his choices or asked to change them when it’s for what he considers the best outcome. (He can see timelines and outcomes where he didn’t summon us to the past and the disasters that could’ve been including Lucifer getting forever trapped in Cocytus)
Also directly confirming he knows we are from the future could alter the timeline too. Anything he says or does could alter the timeline negatively so he pretends to be ignorant or remain oblivious when that’s not the case and Solomon knows it.