Piers Gaveston, the lover of Edward II, King of England. Their relationship started before 1307 and continued probably right up to near Piers death by execution in 1312.
Leo on his site Genealogics here shows this Piers with just the one child Joan de Gaveston, his legitimate daughter who died age 13. Leo does not mention the illegitimate daughter Amie de Gaveston who married John de Driby, but she is mentioned in various other sources like these.
The below text comes from the Dictionary of National Biography, 1922 edition's article on "Piers Gaveston"
Gaveston, Piers, Earl of Cornwall (d. 1312), favourite of Edward II, was the son of a Gascon knight who had earned the favour of Edward I by his faithful service. He was brought up in the royal household as the foster-brother and playmate of the king's eldest son Edward, and thus early gained an ascendency over him. His character, as given by contemporary writers, is not altogether unfavourable. Baker of Swynebroke describes him as graceful and active in person, intelligent, nice in his manners, and skilled in arms. 'There is not authority for regarding Gaveston as an intentionally mischievous or exceptionally vicious man;' but by his strength of will he had gained over Edward a hold which he used exclusively for his own advancement. He was brave and accomplished, but foolishly greedy, ambitious, ostentatious, and imprudent. 'The indignation with which his promotion was received was not caused... by any dread that he would endanger the constitution, but simply by his extraordinary rise and his offensive personal behavious' (Stubbs, Const. Hist. chap. xvi.) His master's inordinate affection for him entirely turned his head; he scorned the great lords, and brought upon himself the envy and hatred of the very men whom he should have conciliated. His pride, says a contemporary, would have been intolerable even in a king's son. 'But I firmly believe,' continues the writer, 'that had he borne himself discreetly and with deference towards the great lords of the land, he would not have found one of them opposed to him' (Chron. Edward I and II, ii. 167).
Little is said of Gaveston in the reign of Edward I; but Hemingburgh (ii.272) has handed down a curious story of his having instigated the prince to ask for him the county of Ponthieu, a demand which so enraged the king that he drove his son from his presence. Edward I determined to separate the friends, and on 26 Feb 1307, at Lancercost, issued orders for the favourite's banishment, to take effect three weeks after 11 April, and bound both him and the prince never to meet again without command. But the king died on 7 July, and Edward II's first act after his accession was to recall his friend. The disgrace of Ralph Baldock, bishop of London, the chancellor, and of Walter Langtop, bishop of Coventry, the treasurer, who was regarded as Gaveston's enemy, immediately followed. A large sum of money, amounting to 50,000 pounds, Langton's property, was seized at the New Temple, and, it is said, was given to the favourite, who also received from Edward a present of 100,000 pounds, taken from the late king's treasure, a portion of which sum had been set aside for a crusade to the Holy Land. All this wealth Gaveston is reported to have transmitted to this native country of Gascony.
On 6 Aug 1307 Gaveston received a grant of the earldom of Cornwll and of all lands late belonging to Edmund, late earl of Cornwall, the son of the king of the Romans; and on 29 Oct following he was betrothed to Margaret de Clare, sister of the young Earl of Gloucester, and the king's own niece, and obtained with her large possessions in various parts of the kingdom. In his promotion to the earldom he had the support of the Earl of Lincoln, and by his marriage he became allied to a powerful house. But his pride could not be satisfied, and, as an instance of his personal vanity, one of the chroniclers notices that by royal command persons were forbidden to address him otherwise than by his title, an unusual practice at that period (ib. ii. 157). On 2 Dec he held a tournament at Wallingford, in honour of the king's approaching marriage, but only increased his unpopularity with the barons, and particularly with the Earls of Warenne, Hereford, and Arundel, by defeating them in the lists.
On 30 Dec Gaveston was appointed regent of the kingdom during Edward's absence in France on his marriage, although the king did not acutally depart till 22 Jan 1308, and was absent till 7 Feb. On 25 Feb was celebrated the coronation, which had originally been appointed to take place a week earlier, and is even said to have been deferred on account of the growing discontent against the royal favourite. Here Gaveston's display eclipsed his rivals, and it is noticed as a special affront to the other nobles that he was appointed to carry in the procession the crown of St Edward. His other services were the redemption of the 'curtana' sword, and the fixing of the spur on the king's left foot. His ostentation and the king's obtrusive partiality for him are also said to have disgusted the queen's relatives who were present, and who, on their return home, imparted their prejudice to the king of France. Seeing the storm rising, Edward postponed the meeting of the council, but at length, on 28 April, the barons assembled, and at once proceeded to call for Gaveston's banishment. Hugh Despenser (1262-1326) [q.v.] is said to have been the only man of importance who attempted to defend him. The king was forced to comply, and on 18 May issued his letters patent which proclaimed the sentence, the prelates undertaking to excommunicate Gaveston if he disobeyed; but, to softed the blow, Edward heaped fresh gifts upon him, and on 16 June appointed him lieutenant of Ireland, and at the same time prayed the pope to intervene for his protection. Gaveston sailed for his new command on 28 June from the port of Bristol, whither he was accompanied by the king in person, and remained in Ireland for a year. He established himself as Edward's representative at Dublin, and reduced the hostile septs in the neighbourhood, restored the fortresses, and carried out other works. But the king could not exist without his friend. Before many months had passed he was working for his recall; in April 1309 he tried to move the king of France to intercede in his favour, and, although parliament refused to sanction the favourite's return, he at length prevailed upon the pope to absolve him. Early in July Gaveston was welcomed by the king at Chester.
At an assembly of the barons at Stamford on 27 July, the king accepted the articles of redress previously presented to him by the parliament, and, through the mediation of the Earl of Gloucester, the Earls of Lincoln and Warenne were drawn over to Gaveston's side, and a large number of the barons gave their formal assent to his return. But Gaveston's insolence only increased, and he appears to have chosen this inopportune moment for forcing upon the earls opprobrious nicknames in ridicule of their personal peculiarities or defects. The Earl of Lincoln was 'burstbelly' (boele crevee); Lancaster was 'the fiddler' (vielers), or 'play-actor' (histrio); Gloucester, his own brother-in-law, was 'horeson' (filz a puteyney); and Warwick was 'the black hound of Ardern.' 'Let him call me hound,' exclaimed the latter; 'one day the hound will bite him' (Chron. Lanercost, p. 216). He is specially accused at this period of appropriating the revenues of the kingdom to such an extent that the king was straitened for means to support the charges of his court, and the queen was subjected to unworthy reductions, of which she bitterly complained to her father.
Within three months of his return Gaveston had again estranged those to whom he had but just now been reconciled. A council was summoned at York in October, but Lancaster and others refused to appear. Fearful for his safety, Edward kept Gaveston close to his side, and they passed the Christmas of 1309 togethre at Langley. In February 1310 the bishops and barons were again summoned, and when they met in March the barons attended in arms. Edward was compelled to submit to the election of a commission of ordainers invested with power to frame ordinances for the reform of the government. In February Gaveston had withdrawn from court. In September the king marched against the Scots, and was joined by Gaveston at Berwick, where they remained until the end of July of the next year (1311). But then Edward was obliged to return to London to meet the parliament, which had been summoned for 8 Aug. Gaveston was therefore placed for safety in Bamborough Castle. In the parliament the new ordinances were presented to the king for confirmation, one of them specially requiring the perpetual banishment of the favourite. Edward resisted for some time, but on 30 Sept was forced to assent. By the terms of his sentence Gaveston was called upon to leave the kingdom, sailing from the port of Dover before the feast of All Saints, and Scotland, Ireland, Wales, and Gascony, as well as England, were forbidden to him. He is said to have first attempted to pass into France, but fearing to be made prisoner, he retired to Bruges in Flanders, where, however, through the hostile influence of the king of France, he was badly received. At Christmas he secretly returned to England, and for a while remained in hiding, moving from place to place. At the beginning of 1312 the king went to York, recalled Gaveston to his side, and restored his estates. On 18 Jan he publicly announced his favourite's return and reinstatement. The hostile barons, with Lancaster at their head, at once took up arms, and demanded Gaveston's surrender, while Archbishop Winchelsey publicly excommunicated him and his abetters. The king and Gaveston now drew away further north, leaving York on 5 April, and remained at Newcastle till the beginning of May. But the barons were now approaching. Edward and his favourite, hastily retiring to Tynemouth, took ship and fled to Scarborough, a place of great strength, but not prepared to stand a siege. The king withdrew to York. Meanwhile the barons seized all Gaveston's goods in Newcastle, and advanced against Scarborough, which the Earls of Warenne and Pembroke were appointed to besiege. On 19 May Gaveston surrendered to Pembroke, who pledged himself for his prisoner's personal safety, and set out with him towards Wallingford, there to await the meeting of parliament in August. Arrived at Deddington in Oxfordshire, Pembroke left Gaveston under a guard, and departed on his own affairs. Scarcely had he gone, when Warwick, hearing that his hated enemy was so close at hand, surprised him before dawn on 10 June, and, making him his prisoner, carried him off to his castle of Warwick. There, on the arrival of Lancaster, Hereford, and Arundel, a consultation was hastily held, and it was determined to put their prisoner to death. The place chosen for the execution was Blacklow Hill, otherwise called — prophetically, as the chroniclers say — Gaversike, about a mile north of the town, in order that the Earl of Warwick might be relieved of immediate responsibility. There his head was struck off on 19 June 1312, in the presence of Lancaster and his confederates; Warwick, however, apparently again with a view to future justification, remaining behind in his castle. The body was taken possession of by the Dominicans or preaching friars of Oxford, in which city it lay for more than two years. It was thence conveyed by Edward's orders to King's Langley in Hertfordshire, and buried there on 2 Jan 1315, with great ceremony, in the house of the Dominicans, which had been lately built and endowed by the king. Gaveston left but one child, a daughter. His widow afterwards married Hugh de Audley the younger.
Source: Chronicles of Trokelowe, Lanercost, Walsingham, Baker of Swynebroke; Chron. of the Reigns of Edward I and Edward II (RollsSer.); Dugdale's Baronage; Stubbs' Const. Hist.; W.P. Dodge's Piers Gaveston, 1899; art. supra Edward II. In Marlow's tragedy of Edward II, Gaveston plays a prominent part.] — E.M.T.