Biography
War Is Hell? Not to this guy.
Fighting is everything to the Blood Knight. He lives for it. It's not winning or losing, morality, the motives of his allies, or even the glory that drives this guy so much as it is the opportunity for a good fight.
A Blood Knight can be of any morality whatsoever, although Anti Heroes and Anti Villains tend to be most common.
Heroic examples will frequently be The Big Guy in an ensemble, the character most likely to solve his problems by force of arms. They might make the less violent members of the crew a little nervous, especially if they go off on a hair trigger. He may merely enjoy the challenge and not hurting others necessarily; some don't hurt people unprovoked since they have a sense of right and wrong.
The Blood Knight doesn't even have to be a particularly violent man most of the time. A common version found in Eastern fiction is the Wandering Martial Artist, who Wanders the Earth looking for strong opponents to test his skills against. This might be coupled with a love of fair duels and a desire to challenge the best and strongest. This type still enjoys the thrill of the fight, but usually eschews the death and bloodshed aspect. A living opponent, after all, can improve their skills and provide an even better challenge later. Defeat Means Friendship is a common occurrence with these guys, their opponent's or their own.
As an antagonist, he has a good chance of being an Anti-Villain, since he doesn't want to kill the heroes, necessarily, just fight them. If he can find someone tough enough to beat him he might undergo a Heel–Face Turn and join the hero's team, or simply gain a newfound respect for his foe that he didn't have before. He might deliberately disadvantage himself in order to make fights last longer and loves to reveal that he is not left-handed. Despite the brutality that this trope implies, it's not uncommon for them to be a Noble Demon as well when they want an exciting fight on specific terms or when they reject unfair advantages because it would make the fight no fun. He may even betray his boss if he insists on interfering to pursue and obsess over his foe on his own terms. Less pleasant ones may do all kinds of horrible things to provoke their opponents into fighting them. Though if they specifically love to kill (rather than fight) they are a Psycho for Hire.
Personality-wise, more evil ones may be a Flat Character (and quite possibly The Brute) who just shouts "Maim! Kill! Burn!". Good/Sympathetic ones are usually more sophisticated/developed and can have aspects of the Warrior Therapist, Warrior Poet or Cultured Warrior. He might be a normal, jocular guy when he's not brawling, or he might take the fight so seriously that he blocks out everything else and will therefore live only for battle. In some cases, the Blood Knight fights because he's looking for a way to die with meaning.
A War God is very often one of these though he could also be Ax-Crazy or just The Sociopath. If there's a whole society of guys who like combat, you've got a Proud Warrior Race. If the character likes the killing part more than the 'fighting' part, they're a Psycho for Hire. (In fact it's not uncommon for Blood Knights to also uphold Thou Shalt Not Kill). The Egomaniac Hunter also thrives on aimless violent thrill and loves a worthy quarry instead of an opponent. If a character is in it for the challenge rather than just the fight, then we've got a Spirited Competitor. The Blood Knight's love of combat may be platonic, or it may have sexual undertones. It could also overlap with Ax-Crazy if their love of fighting crosses the line into psychopathic violence and mental and emotional instability.
Sub-Trope of In Harm's Way. Sister Trope to Combat Sadomasochist, The Real Man, and Boisterous Bruiser. Compare Cavalier Competitor and, for a more general trope, Challenge Seeker. Also compare Sadist, whose favorite part of fighting is the pain and suffering of his opponent. May be from a Martyrdom Culture and will nearly always believe that War Is Glorious. If he (or she, though it's much rarer, however; see Lady of War) is in the military, then he will almost inevitably be a Colonel Kilgore. A Monster Knight has a high chance of being one. A more violent example that nonetheless fights on the side of good may (or may not) be a Sociopathic Hero. It also has nothing to do with a knight who uses Blood Magic. Contrast Shell-Shocked Veteran, who is of the opposite mindset (also contrast War Is Hell).
Oh, just in case it wasn't clear, the character doesn't have to be a literal knight for this trope to apply. It is about the attitude, not the rank.
It should be clear by now that this character loves laying the hurt. And ironically, it's because of this that these characters are quite likely to get saddled with a No-Harm Requirement at some point. A mission's success may forbid the use of any violence, a target may be too dangerous to hurt recklessly, this particular opponent may be too precious to hurt, etc. Whatever the case, it's often quite ordeal for many Blood Knights to handle such a challenge. Beating opponents to a pulp? Easy peasy. Putting them out of commission without hurting them? Not so much...
Contrast with Reluctant Warrior, the exact opposite of this trope: rather than enjoying the thrill of battle, they instead treat it as a last resort.
Not to be confused with Blood-Splattered Warrior, though they sometimes overlap.
