There are variations on the theme, but the basic standard narrative is that Simon the Fox is the epitome of evil, with the Widow Lovat being a victim and Lord John Murray the white knight defending the honour of his family. The following is a summary from Electric Scotland: (http://www.electricscotland.com/history/nation/fraser.htm).

			FRASER, SIMON, 12th Lord Lovat, one of the most remarkable of the actors in the rebellion of 1745, was the second son of Thomas Fraser, styled of Beaufort, by Sybilla, daughter of Macleod of Macleod, and was born in 1667. Beaufort was another name of Castle Counie, the chief seat of the family, and did not belong to Simon’s father at the time of his birth. He had a small house in Tanich, in the parish of Urray, Ross-shire, where it is supposed that the future Lord Lovat was born. At the proper age he became a student at King’s college, Old Aberdeen, the favourite university of the Celts, and in 1694, while prosecuting his studies, he accepted of a commission in the regiment of Lord Murray, afterwards earl of Tullibardine, procured for him by his cousin, Hugh Lord Lovat. Having, in 1626, accompanied the latter to London, he found means to ingratiate himself so much with his lordship, that he was prevailed upon to make a universal bequest to him of all his estates in case he should die without make issue. On the death of Lord Lovat soon after, Simon Fraser began to style himself master of Lovat, while his father, “Thomas of Beaufort,” took possession of the honours and estates of the family. To render his claims indisputable, however, Simon paid his addresses to the daughter of the late lord, who had assumed the title of baroness of Lovat, and having prevailed on her to consent to elope with him, would have carried his design of marrying her into execution, had not their mutual confident, Fraser of Tenechiel, after conducting the young lady forth one winter night in such precipitate haste, that she is said to have walked barefooted, failed in his trust, and restored her again to her mother. The heiress was then removed out of the reach of his artifices by her uncle, the marquis of Athol, to his stronghold at Dunkeld.       Determined not to be baulked in his object, the master of Lovat resolved upon marrying the lady Amelia Murray, dowager baroness of Lovat; but as she would not consent to the match, he had recourse to compulsory measures, and, entering the house of Beaufort, or Castle Dounie, where the lady resided, he had the nuptial ceremony performed by a clergyman whom he brought along with him, and immediately afterwards, it is said, forcibly consummated the marriage before witnesses. He afterwards conveyed her, her brother Lord Mungo Murray and Lord Saltoun, whom he had forcibly seized at the wood of Bunchrew, on his return from a visit to her at Castle Dounie, to the island of Aigas, where he kept them for some time prisoners. Having by these proceedings incurred the enmity of the marquis of Athol, who was the brother of the dowager Lady Lovat, he was, in consequence of a representation made to the privy council, intercommuned, letters of “fire and sword” were issued against him and all his clan, and on Sept. 5, 1698, he and ten other persons of the name were tried, in absence, before the high court of justiciary for high treason, rape, and other crimes, when being found guilty of treason, to which the lord advocate restricted the charges in the indictment, they were condemned to be executed, and their lands declared forfeited. His father having died in 1699, he assumed the title of Lord Lovat, but in consequence of the proceedings against him he was compelled to quit the kingdom. After a short stay in London, he went to France, for the purpose of lodging a complaint against the marquis of Athol with the exiled king at St. Germains; after which he had the address to obtain an interview with King William, who was then at Loo in the United Provinces; and having obtained, through the influence of the duke of Argyle, a remission of his sentence, and a pardon of all crimes that could be alleged against him, – which, however, was restricted, on passing the Scottish seals, to the crime of which he had been found guilty, – he ventured to return to Scotland. He was immediately cited before the high court of justiciary, on 17th February 1701, for the outrage done to the dowager Lady Lovat, and, not appearing, he was outlawed. On the 19th February 1702 her ladyship presented a petition against him for letters of intercommuning, for levying the rents of the Lovat estates, which a second time were granted against him and his abettors. He now deemed it advisable to return to France, which he reached in July of that year, after the accession of Queen Anne to the throne. Previous to his departure from Scotland, he had visited several of the chiefs of clans and principal Jacobites in the lowlands, and engaged them to grant him a general commission engaging to take up arms in support of the Stuart cause; possessed of which he immediately joined in all the intrigues of the exiled court of St. Germains, and even managed to obtain some private interviews with Louis the Fourteenth. By that monarch a valuable sword and some other tokens of reminiscence were bestowed on him as a mark of his confidence. He had also some meetings with two of the French ministers of state, on a project which he had proposed to the ex-queen, Mary of Modena, acting in her son’s name, a boy at that time only fourteen years of age, for the invasion of Scotland and the raising of the Highland clans.       He returned to Scotland in 1703, with a colonel’s commission in the Pretender’s service, and accompanied by John Murray, brother of Murray of Abercairney, who was authorised to ascertain if Lovat’s representations, as to the intentions of the Jacobite chiefs, had been warranted by them. Immediately after his return he had interviews with his cousin Stuart of Appin, Cameron of Lochiel, the laird of MacGregor, Lord Drummond, and others, on the subject of a rising, but meeting with little encouragement, he resolved to betray the whole plot to government; which he did in a secret audience with the duke of Queensberry, who was then at the head of Scottish affairs. On his re-appearance in Scotland, letters of “fire and sword” had again been issued against him and his followers, and he prevailed on Queensberry to grant him a pass to London, that he might be out of the reach of danger. With his grace he had some more secret interviews in London, and soon after he returned to France, by way of Holland, with the object of obtaining for government further secret information about the projects of the exiled court. In passing through Holland he assumed the disguise of an officer in the Dutch service, but soon after his arrival in Paris, he was, by the french government, at the instance of the exiled queen, arrested, sent to the Bastille, and afterwards imprisoned for three years in the castle of Angouleme, and seven years in the city of Saumur, where he is said to have taken priest’s orders, and become a renowned popular preacher.       After making many fruitless efforts to regain his liberty, – the exiled court having refused to sanction his release, – he at last resolved, on the death of Queen Anne, to endeavour to make his escape, which he effected with the aid of Major Fraser, one of his kinsmen, who had been sent over by his clan to discover where he was, and to learn his intentions, in the event of an insurrection in favour of the Stuarts. Reaching Boulogne in safety, and there hiring a boat, they sailed on 14th November 1714, and after a storm, landed at Dover next afternoon. On his arrival in London, he kept himself concealed for some time; but at the instigation of his enemy the marquis of Athol, a warrant was issued against him, and on the 11th of the following June, he was arrested in his lodgings in Soho Square, and, with the major, kept for some time in a sponging house, but at last obtained his liberty, on the earl of Sutherland, John Forbes of Culloden, and some other gentlemen, becoming bail for him to the extent of £5,000.       He remained in London till October 1715, when the rebellion having broken out, he returned to Scotland as one of his brother john’s attendants, being still under the sentence of outlawry. In a vindication of his conduct addressed to Lord Islay he says, that on this occasion he was taken prisoner at Newcastle, Longtown, near Carlisle, Dumfries, and Lanark, but succeeded in reaching Stirling. He proceeded thence to Edinburgh, to embark at Leith for the north, but had not been there two house when he was apprehended by order of the lord justice clerk, and would have been sent to the castle had he not been delivered, he does not say how, by Provost John Campbell. A few days after he sailed from Leith with John Forbes of Culloden, but their vessel was pursued and fired upon by several large Fife boats in possession of the rebels. On arriving in his own country, he was just in time to be of considerable service to the royal cause and to his own interests. Joining two hundred of his clan who were waiting for him under arms in Stratherrick, he concerted a plan with the Grants, and Duncan Forbes of Culloden, afterwards president of the court of session, for recovering Inverness from the rebels, in which they were successful. For his zeal and activity on this occasion he had his reward. The young baroness of Lovat had married, in 1702, Alexander Mackenzie, younger of Prestonhall, who thereupon assumed the name of Fraser of Fraserdale; but engaging in the rebellion of 1715, he was obliged to leave the country, and being outlawed and attainted, his liferent of the estate of Lovat was bestowed, by a grant from the Crown, dated 23d August 1716, on Simon, Lord Lovat, “for his many brave and loyal services done and performed to his majesty,” particularly in the late rebellion. A memorial in his lordship’s favour, signed by about seventy individuals, including the earl of Sutherland, the members of parliament and the sheriffs of the northern counties, having been presented to the king, George the First, his pardon had been granted on the 10th of the preceding March, and on the 23d June following he had a private audience with his majesty. In 1721 he voted by list at the election of a representative peer, when his title was questioned. His vote was again objected to at the general elections of 1722 and 1727. In consequence of which, he brought a declaration of his right to the title before the court of session, and their judgment, pronounced July3, 1730, was in his favour. To prevent an appeal, a compromise was entered into with Hugh Mackenzie, son of the baroness, who, on the death of his mother, had assumed the title, whereby, for a valuable consideration, he ceded to Simon Lord Lovat his claim to the honours and his right to the estate after his father’s death.       Although Lord Lovat had deemed it best for his own purposes to join the friends of the government in 1715, he was, nevertheless, throughout his whole career, a thorough Jacobite in principle; and in 1740 he was the first to sign the Association for the support of the Pretender, who promised to create him duke of Fraser, and lieutenant-general, and general of the Highlands. On the breaking out of the rebellion in 1745, he sent his eldest son, much against the young man’s inclination, with a body of his clan to join the army under Prince Charles, while he himself remained at home. After the disastrous defeat at Culloden, the young Pretender took refuge, on the evening of the battle, at Gortuleg, the house of one of the gentlemen of his clan, near the Fall of Foyers, where his lordship was then living, and not at Castle Dounie, as erroneously supposed by Sir Walter Scott. According to Mrs. Grant of Laggan’s account of the meeting, Lovat expressed attachment to him, but at the same time reproached him with great asperity for declaring his intention to abandon the enterprise entirely. “‘Remember,” said he fiercely, “your great ancestor, Robert Bruce, who lost eleven battles, and won Scotland by the twelfth.” Lovat himself afterwards retired from the pursuit of the king’s forces to the mountains, but not finding himself safe there, he escaped in a boat to an island in Loch Morar. Thither he was pursued, taken prisoner, being found concealed in a hollow tree, with his legs muffled in flannel, and carried to London. His trial for high treason commenced before the House of Lords, March 7, 1747, He was found guilty on Marcy 18; sentence of death was pronounced next day; and he was beheaded on Tower Hill, April 9, 1747, in the eightieth year of his age. His behaviour while in the Tower was cheerful and collected. When advised by his friends to petition the king for mercy, he absolutely refused, saying he was old and infirm, and his life was not worth asking. His estates and honours were forfeited to the Crown, but the former were restored in 1774 to h is eldest son, as already mentioned earlier.       Lord Lovat’s appearance, in his old age, was grotesque and singular. Besides his forced marriage with the dowager Lady Lovat above described, he entered twice, during that lady’s life, into the matrimonial state; first, in 1717, with Margaret, fourth daughter of Ludovick Grant of Grant, by whom he had two sons and two daughters; and, secondly, in 1733, after that lady’s death, with Primrose, fifth daughter of John Campbell of Mamore, brother to the duke of Argyle. By this lady he had one son. The lady’s objections to the marriage he is said to have overcome by the following stratagem: She received a letter purporting to be from her mother, in a dangerous state of health, desiring her presence in a particular house in Edinburgh. On hastening to the house indicated, she found Lovat waiting for her there, when he informed her that the house was devoted to purposes which stamped infamy on any female who was known to h ave entered it. To save her character, she married, him, but is said to have been treated by him with so much barbarity as to be obliged to leave his house, when he was forced to allow her a separate maintenance. Of the eldest son, General Simon Fraser, born 19th October, 1726, an account has been already given. The second son, Alexander, born in 1729, after serving in the army abroad, returned to the Highlands with the title of brigadier. Janet, the elder daughter, married Macpherson of Clunie. Sybilla, the younger, died unmarried. On the faith of his ‘Memoirs written by himself in the French language,’ Lord Lovat has been admitted into Walpole’s list of Royal and Noble Authors.