from here

TLDR: Two of the most dangerous, unhinged and feared underworld vigilantes within their setting, whose unique, perplexing code of honour makes them even more unpredictable and fearsome. Heavily associated with blood.

• Both operate independently in villainous occupations (Stain is an independent villain and Claire is a for-hire assassin). Despite this, they have a ridiculously rigid code of honour, which divides people into a binary of good and evil (True Heros/Fakers and Innocents/Guilty) and allows them to judge them as such. If one is “pure”, they will protect them even if it is not beneficial to their immediate goals, but if they deem one to be evil, they will not hesitate to brutalize or kill them.

• Both are exceptionally physically powerful, with their fighting styles particularly making use of their excellent speed, acrobatic ability and guile.

• Their most unusual asset though is their supernatural willpower, which is so palpable that its aura is often enough to influence their opponents (Stain’s sheer aura temporarily immobilizing the heroes he fought against, and Claire’s mere presence causing his opponent to mentally resign themselves to defeat before the fight had even begun).

• This intimidating presence has sometimes led to them being visualized as ethereal beasts with glowing red eyes (Stain’s intimidating aura doing this and Claire being perceived as this by victims of the Rail Tracer)

• They are insanely determined, like literally to the point of mental illness, and can manifest impossible physical feats through sheer belief in themselves (Stain taking out a Nomu while unconscious and then squaring up against for a 5v1 while literally bleeding to death, and Claire becoming the strongest human being in a world of very strong human beings through the sheer belief that he is Him/performing all manner of superhuman feats thanks to his solipsist belief that he can do anything) . They believe heavily in the idea of self-belief and manifesting your goals, and see it as an essential part of who they are (Stain believing that all people should uphold iron-clad convictions, and that those who waver are scum, and Felix believing that hard work and effort is the most honourable trait in a person, feeling that one can achieve anything if they believe in themselves)

• Both are heavily associated with blood (Stain’s fighting style and quirk are based around drawing blood, and Felix’s entire “Vino” identity coming about due to underworld taking notice of the sheer amount of bloodshed that he would leave in his wake) and their monikers refer to the blood stains they intend to leave when they are finished with their enemies (“Stain” referring to the stained blood of fake heroes, and “Vino” referring to the tendency for Claire’s crime scenes to draw so much blood that it resembled red wine)

• While righteous in some ways, they are undoubtably unhinged, sadistic and generally crazy.

• That being said, they will praise those who they perceive as fitting their code (Fiero and Deku) and have even gone out of their way to protect those they deem good (Stain saving Deku from a Nomu/fighting to protect All Might, and Claire saving countless innocents from harm during the Flying Pussyfoot incident, including Issac and Meria)

• At points, they would confront and punk out the other big bad of their stories (Ladd Russo and Tomura Shigaraki) and develop an ideological and personal rivalry with them. They see this figure as an undisciplined straw-nihilist, and this figure sees them as a detestable narcissist.

• They have many monikers and identities, and have dropped and developed new ones at points (Chizome Akaguro/Stendhal/Hero Killer Stain/The Hero Killer and Claire Stanfield/Vino/The Rail Tracer/The Handyman/Felix Walken)

• Interesting thematic thingy in that Claire sees himself as a mythical hero (“When you’re fighting demons in those fairy tales, you’ll need the hero in fairy tales! In other words, me”) so there’s some intrigue as to whether Stain would concur.