Thanos Originally Walked Through A River Of Blood In "Avengers: Infinity War"
Avengers: Infinity War was one of the darkest MCU films to date. Black Panther got a little dark with how they navigated the plot (Killmonger was out here shooting his girlfriend) and Captain America: Civil War touched on darker themes (consequences of actions, capital punishment, maturity in friendship). Still, no film in the MCU was quite as bloody as Infinity War. The film starts with a shot of corpses, and then moves on to kill Idris Elba's Heimdall and Loki.
At the film's conclusion, Thanos retrieves all the Infinity Stones and "snaps" away half of life in the galaxy. SlashFilm sat down with Digital Domain, the company behind Infinity War's stellar CGI, and film's finale came up in the discussion. Apparently, Thanos was supposed to be in a river of blood after he performs the "snap."
The powers that be over at Digital Domain thought it would be a little too dark, but the short interview does give fans a hint at what the bloody scene would look like. The blood was supposed to represent the trillions of lives that Thanos snuffed out. Instead, we were treated to Thanos greeting a baby Gamora in the makeshift environment created by the Soul Stone. The bloody river footage starts at around 3:40, but the entire segment on creating Thanos is worth a watch.