My vague opinion on the DMC timeline, though I need to backtrack and cite my sources a bit tighter at some point. BtN is basically unreadable in english at this point, unfortunately, any information in it unless you can read the actual japanese text should be taken as suspect imo.
Patty 18 years old (game)
Six years post DMC4 (BtN 5 years post DMC4, one year later)
Vergil “visited” fortuna 17-18 years prior to the game & book (lol).
Vergil&Dante (18/19 DMC3, give take nero’s age, 35/36 in DMC4)
Side Note - Lady like 2-3 years younger then Dante at any point.
“Twenty years after the fire”, give or take a bit either direction.
Dante ~28 give or take a bit either direction.
10/11 years prior to DMC3, the fire happens. D&V ~8, given amulet prior to fire during a birthday.
“A decade ago” - BtN, if taken literally that’s stated five years post DMC4 and therefore refers to ~5 years pre DMC4. But like, let’s be for real about DMC2 taking place wherever it’s most convenient for it to have taken place, the devs weren’t even 100% sold on if it was technically canon & not an elseworld until shrugging in BtN even back when the timeline was 3142.
D&V between ~28 & “younger then 36”. ~31 give or take years either direction.
DMC3 => ~9 years later => DMC1 => ~3/4 years later => ANIME => ~4 years later => DMC4 => 6 years later => DMC5
DMC2 “somewhere” in the gap between Anime&4, ostensibly, IIRC. Personal HC - Trish left to explore her own way a bit like a year and a half post DMC1, the plot of DMC2 takes place over like a year or whatever is most convenient for the purposes of the timeline, and then the anime happens.
The devs obviously don’t really care but DF (Nero) and DMC5 (Patty) did give us two specific ages. I can’t remember if the 3manga specifically put D&V forward as 18 at the time but if it didn’t the timeline is technically a bit more wibbly from that end.
