Somebody's Been Reading Dante's Inferno - S4-E2
Stupidity: Chloe finds a new suspect, the cameraman. She goes into his shed and starts talking to him with her back turned towards him as she's looking for the murder weapon; knowing he very well committed the murder. She turns to draw her gun and the cameraman is standing a good 10-12 feet away with an axe, and he says "I wouldn't do that if I were you." A gun vs an axe, the gun will win, she had every ability to shoot him, and secondly going at a murder suspect with no backup is just another stupid move. (00:40:40 - 00:43:10)
Lucifer, Stay. Good Devil. - S1-E2
Stupidity: It takes an awful lot of pointless visits and oblique thinking to simply investigate the known (and apparently only) collaborator and protege of the suspect, who also was on the crime scene. You'd think interrogating the business associate would be standard procedure.
Stupidity: Amenadiel isn't an idiot, but he KEEPS talking to Ghost Dan around other people, then gets surprised when they think he's crazy, or has to catch himself and come up with explanations for his behaviour. Would it be that hard to just stay quiet for a while? Dan understands the situation and wouldn't be offended.
Stupidity: Chloe is talking with Keri, and Chloe without gaining proper distance between herself and the now new murder suspect, accuses her of murdering two people. Chloe draws her firearm on the suspect, however it is knocked out of her hand with a glass bottle. Chloe does a backflip and gains some space. Most cops especially LAPD carry a back-up firearm on their ankle, pocket, AWB holster, vest holster, but not Chloe. She also never carries spare magazines, but they appear when reloads are needed. (00:39:00 - 00:40:00)
Answer: It's Lucifer's blood from when his wings got hit by the bullets. As Lucifer spreads his wings, they're white, and before he wraps them around Chloe, you see a bullet hit his wing above his right shoulder, and the spot turns red. After that, he continues to get shot in the wings before fleeing.
Bishop73
Agreed. His wings take damage and "bleed" similar to how he bleeds when Decker is around.
Ssiscool ★
If they were normal bird's wings, the lower part where there are just feathers should neither bleed like that nor be able to stop bullets, but they are angel's wings, so they behave differently.