One Plus One Equals Two is like a darker version of Batman v Superman in animated form: here we have two titans Homelander and Black Noir fighting each other trying to outsmart the other when both of them are in the crossfires of Vought International and their ruthless scheming.
This evokes the DC Animated Universe somewhat, whilst having an aesthetic closer to some of DC's animated movies and parts of Invincible. This is helped by Homelander having a very 'Batman v Superman' like stand-off with Black Noir during the episode's climactic action sequence. It's very gruesome yet satisfying to see some greatly appreciated backstory on one of TV's greatest villains in recent memory.
One Plus One Equals Two adds up to lore-enriching storytelling for The Boys, and is easily amongst Diabolical's strongest instalments.