Early search matches for 'bad blood' in the relevant sense
Francis Bacon, The History of the Reign of Henry VII (1622/1676) contains this quotation, attributed to King Henry VII in an address to Parliament in October 1492:
At the Battels of Cressy, Poictiers, Agent-Court, we were of Our selves. France hath much People, and few Soldiers. They have no stable Bands of Foot. Some good Horse they have; but these are Forces which are least fit for a Defensive War, where the Actions are in the Assailant's choice. It was our Discords only, that lost France; and (by the power of GOD) it is the good Peace which we now enjoy, that will recover it. GOD hath hitherto blessed my Sword. I have, in this time that I have Reigned, weeded out my bad Subjects, and tryed my good. My People and I know one another, which breeds Confidence : and if there should be any bad Blood left in the Kingdom, an Honourable Forein War will vent it, or purify it. In this great Business let me have your Advice and Ayd.
However, Jerry Weinberger, who edited of an edition of Bacon's History of the Reign of Henry VII in 1996, offers this remark on the supposed speech:
There is no extant copy of this speech. It is as likely that Bacon made it up as that he took it from a record he had at his disposal.
The instance is interesting because it uses "bad Blood" as a metaphor for possible limitations on the unity, confidence, and patriotism of the kingdom's people. Bacon has Henry VII say that a well-funded foreign war will bring the newly happy country even closer together and allow any residual bad blood to be released from the body politic or purified by martial combat. The step from bad blood within a nation to bad blood between nations or between individuals within a nation doesn't seem impossibly large.
It follows that conservatively we have a date of 1622 for the authorship (by Bacon) of this speech attributed to Henry VII, and rather wishfully we have a date of 1492 from Henry VII himself.
Robert Allen, Allen's Dictionary of English Phrases (2008) finds the phrase in the particular sense of "hostility" dating back to 1635:
bad blood hostility or ill feeling: earlier in the form ill blood. The phrase is based on the notion of breeding bad blood, which is found in the 17th cent.
John Reynolds The Triumphs of Gods Revenge 1635
He will hardly leave her either the will or power to thanke him for his courtesie, and so remounts his horse, and presently gallops home to his Mother, whom he acquaints therewith, but yet conceales it from his Father, whereat she seemes not to be a little joyfull, and yet heartily prayeth to God, that this breed no bad blood in her husband, or prove either an incitation to his choller against her selfe, or a propension of revenge against their Sonne.
Reynolds's lurid exposé, The Triumphs of Gods Revenge Against the Crying and Execrable Sin of Murther, Expressed in Thirty Several Tragical Histories, together with Gods Revenge Against the Abominable Sin of Adultery, Containing Ten Several Histories, Never Printed Before, Illustrated with New Sculptures, sixth edition (1679) actually discusses the concept of breeding bad blood on seven occasions, which collectively suggest that the process ultimately involves a poisoning of the body by diabolical intervention. Here, with very little context, are the first six instances in Reynolds's book (Allen's quotation is the seventh instance):
Hautefelia envies her Sister in Law Mermanda's advancement, and contemns her own; she likes not to give the hand to her, whom she knows is by descent her inferiour, and to speak true, prefers a Scarlet Cloak before a Black, and a Sword-man before a Pen-man ; these ambitious conceits of hers, proceeding from Hell, will breed bad blood, and produce mournful effects ; yea, peradventure strangle her, who embraceth and practiceth them.
So alas here it is, that the [he?] first gives way to the devil to take possession of his thoughts and heart, and here it is, that he first assumes bad blood, and suggests bloody designes, against the safety and life of his dear and innocent Mother.
But at last consulting with reason and Religion, with her Soul and God, then her chastity gives a commanding law to her fear, and her innocency to her doubt ; So first hoping, and then praying, that nothing herein might breed bad blood in her Husband, or disturb the tranquillity and sincerity of her marriage ; she watching a fit opportunity, shews her Husband the first Letter, of Borlary to her, with her answer thereof ; and then his second Letter, the which she informs him, she answered with silence and contempt ; ...
And at this discourtesie of Borlary, Castruchio doth now bite his lip with discontent, and hang his head for anger, and from henceforth he begins to assume bad blood, and to conceive dangerous thoughts against him, but as yet the consideration of his own safety or danger makes him patient and silent ; But God will not have him to continue so long, for almost presently we shall see his patience burst forth into violence and impetuosity, and his silence break out into extream choler and indignation against him.
Le Valley not accustomed to receive blows of his Master, was so extreamly incensed hereat, as disdaining the blows for his Master, and his Master for the blows sake, they engender such bad blood in him, as he presently striks a bargain, first with his choler, then with the Devil, that he would now adhere to the request of Blancheville, and so spedily return his Master a sharp requital and bloody revenge for the same ; and indeed from that time forward he never looked on him but with an eye of hatred and detestation.
He prayes and reprayes her to make one Journy more for him to Vercely to see what alterations time may have wrought in the hearts of Cassino and Eleanora ; but she is as averse and wilful, as sh is obstinate and peremptory : And therefore constantly vows, neither to write, nor ever to confer more with them herein. But this resolute answer of the Mother breeds bad blood in the Son, yea it makes a Mutiny in his thoughts, a Civil War in his Heart, and a flat Rebellion in his resolutions against her for the same, to which the Devil (the Arch-enemy, and Incendiary of our Souls) blows the Coals : ...
Early search matches for 'ill blood' in the relevant sense
Although Allen says that the form ill blood is earlier than the form bad blood, I didn't find any unequivocal instances of ill blood as old as Bacon's 1622 instance of bad blood. The one very early possible instance of ill blood that a Google Books search turns up is from Calendar of State Papers, Foreign Series, of the Reign of Elizabeth for the year 1589, which includes the following notice [combined snippets]:
Espernon promised their lives to some Walloons who valiantly defended this town. Divers mislike this, especially bb and his followers. Ill blood grows of this "and will take root upon religion although it be but ambition." On Saturday afternoon some of the Walloons were appointed to be hanged. Espernon protested to the King and told of his promise, which the King said "was too much for him and said that it was his custom to play those parts." Espernon thereupon departed, but Lyly hopes that it will be remedied, though it is this nation's destiny "that having put their business in good form, by some frantic accident to deform all."
I don't know what to make of the dipping into and out of quotations that occurs in this paragraph, but I suspect that a later writer may be connecting old quotations with more recent interpolations, in which case the "ill blood" language—not being part of a quotation—may be considerably more recent than 1589. The language overall doesn't sound very Elizabethan.
Ill blood does show up in a number of seventeenth-century sources, such as in "A New Song of the Times" (1683) reprinted in Poems On Affairs of State: From The Time of Oliver Cromwell, to the Abdication of K. James the Second (1697):
Algernon Sidney, /Of Commonwealth Kidney,/ Compos'd a damn'd Libel (ay marry was it)/ Writ to occasion/ Ill Blood in the Nation/ And therefore dispers'd it all over his Closet.
And Daniel Defoe, "The Shortest Way to Peace and Union, &c." (1703) has this very incisive (and modern-sounding) analysis of the bad effects of zealots of the status quo:
First, Those warm Gentlemen of the Church of England, who think they do GOD good Service in railing at the Dissenters, as Subverters of the Church and of the Monarchy, and show their Wit in first painting the Robe of Rebellion in all its bloody Colours, and then dressing up the Dissenter in it, as if the Coat fitted none but him, are very much to blame; my Charity disposes me to hope they are unwilling so ; but certainly they are effectually and eventually Enemies to the Peace of the Church, and the Property of the Crown ; all the Aversion of Parties is owing to them ; all the ill blood which is to be found among the Dissenters, is owing to the Menaces of these furious People, who in Print and in Pulpit, Entitle the whole Church and Government to the Extasies of their Passions, and speak in the plural Number, as if they were then commanded to Curse Jacob.
From the use of bad blood in Bacon (1622) and Reynolds (1635), I infer that the expression began as a literal description of supposed physiological corruption of a person's blood leading to hatred and violence. Bacon doesn't suggest any cause for the metaphorical bad blood that he has Henry VII suggest may lurk in the newly united Kingdom of England in 1490; Reynolds is quite ready to view it as a poisoning of the blood (and souls) of easily deceived human beings by the devil.
Bacon suggests that bad blood can be purged ("vented") or purified. Reynolds seems to see it as a kind of toxic madness that one cannot escape but by the grace of God.
Today, of course, most people don't take the "blood" aspect of bad blood seriously: bad blood is something that arises between people, not within them, and saying that "bad blood exists between them" isn't metaphorically much stronger than saying that "those two have a history"—suggesting an origin in an old grievance or interfamily feud.