Cain
The LORD said, "What have you done? Listen! Your brother's blood cries out to me from the ground. Now you are under a curse and driven from the ground, which opened its mouth to receive your brother's blood from your hand. When you work the ground, it will no longer yield its crops to you. You will be a restless wanderer on the earth."
Cain said to the LORD, "My punishment is more than I can bear. Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me."
But the LORD said to him, "Not so; if anyone kills Cain, he will suffer vengeance seven times over." Then the LORD put a mark on Cain so that no one that found him would kill him. So Cain went out from the LORD'S presence and lived in the land of Nod, east of Eden.
- Genesis 4:10-16 (New International Version)
Corporeal Forces: 4 Strength: 6 Agility: 10
Ethereal Forces: 5 Intelligence: 10 Precision: 10
Celestial Forces: 5 Will: 10 Perception: 10
Skills: Dodge/2, Emote/6, Fighting/2, Knowledge (Lore of the War/6, Lore of Relics/6, Lore of the Lost/6), Languages (Just about all of them/3), Ranged Weapon/1 (pistol), Savoir-Faire/1, Small Weapon (knife/1, rock/2)
Songs: Banishing (Corporeal/1), Calling (Corporeal/1), Creation (Corporeal/1), Darkness (Corporeal/1), Direction (Corporeal/1), Empathy (Corporeal/1), Fire (Corporeal/1), Forgetting (Corporeal/1), Freedom (Corporeal/1) Harmony (Corporeal/1), Light (Corporeal/1), Might (Corporeal/1), Retribution (Corporeal/1), Spirit Speech (Corporeal/1), Succor (Corporeal/1), Symphony (Corporeal/3), Visions (Corporeal/1), Water (Corporeal/1). Note that Cain doesn’t exactly advertise the fact that he has access to some lost Songs.
'Relics': The Mark of Cain. This isn't precisely a relic, of course, but it's close enough. The Mark is an unknown word, thought to be very Old Angelic, inscribed on Cain's forehead. The Mark is only consciously visible to those with Symphonic Awareness, but mortals and animals will be subconsciously aware of it.
The Mark apparently is responsible for making Cain immortal: he cannot die of natural causes, will eventually recover from the worst wounds, never gets sick and never ages. However, if he spends more than one month in the same locale, the Mark becomes extraordinarily painful. Cain can only stop the pain by traveling at least 100 miles away, and not return to the original place for a full year.
Mortals will find themselves fiercely resisting the idea of killing Cain, coming up with the flimsiest excuses to avoid doing so. Those with Symphonic Awareness will not suffer from this. However, angels aren't about to disobey God, demons know that Lucifer (for reasons of his own) has declared this mortal off-limits, and there's quite a bit of mythology among those in the know about just what dark Fate awaits the killer of Cain. Note that none of this precludes someone from beating him to a pulp: they'll just avoid killing him.
Cain has seen everything. He's been wandering the earth for the last twenty thousand years, and has had the unenviable advantage of watching the whole War, from start to finish. He's also watched his name became a synonym for murder, violence and bestial behavior.
By any rational standard, one would think that Cain's been punished enough for his crime. At various times in human history, he's been hung, stabbed, crucified, beaten, tortured, shot, burned, gassed, buried alive and generally been at the brink of death more times than he can count. There were times when he was driven mad by the pain and endless days… but he always recovered. He'll always recover. In many ways, that's the worst part.
Why he's still here is a topic of some debate. Demons mostly use Cain as another bit of evidence that God's a tyrannical master, ready to inflict punishments all out of proportion to the crime, although some just say that Lucifer has a special plan for this particular mortal. Angels, on the other hand, suspect that Cain's punishment was actually an act of mercy: he has obviously met his Fate, but the Eden Experiment that eventually caused him to be born was tainted by celestial interference. There's a faint chance that he might achieve his Destiny, and so avoid a rigged damnation. Unfortunately, nobody really knows.
If properly used, Cain is an amazing resource of information. He's had a ringside seat for the entire War, and his memory is excellent (too excellent, really). Long lost prophecies, ancient battles, dead languages, legends of artifacts and Songs: the more obscure it is, the likelier it is that it's in his head somewhere. By now, he's so weary that he'll tell anyone anything they want to know.
Cain's personality and whereabouts will differ, depending on the Brightness of the campaign. In Bright Campaigns he's definitely more hopeful than above, and can be found doing any job that allows for frequent travel. He might even have a family (or twelve). Cain, in this setting, is sure that there's a reason for his endless existence, and will be actively trying to discover it. He will help those who he considers on the side of Right, but you have to convince him first that you actually are on the side of Right. Best if you also have something to trade for the information you need.
In Dark campaigns, however, he's a bum. Go to the darkest corner of the darkest city on Earth, and there Cain will be, futilely attempting to drink (or drug) himself to death. Getting information will be easier to arrange (bring a good supply of any drug), but Cain's a malicious bastard on this setting, so be prepared to get information that's misleading and incomplete (although he's usually too cowardly to lie outright).
In silly campaigns, drop the 'need to wander' requirement (or tone it down drastically): he's tending bar in your favorite watering hole. He's also addicted to answering questions obscurely, or in languages that haven't been spoken in four thousand years, but that's the price you pay for getting your intelligence from a bartender.