After Piers Gaveston returned to England from his second exile in the summer of 1309 - he'd been in Ireland, proving surprisingly effective as Lord Lieutenant - he demonstrated that he'd learnt little from the experience and was as arrogant as ever. Secure in Edward II's love and favour, he proceeded to continue annoying the great men of the realm. The contemporary Vita Edwardi Secundi says "The earls and barons he despised, and gave them insulting nicknames" (turpia cognomina).
The only nickname that's strictly contemporary is the one Piers gave to Guy Beauchamp, earl of Warwick, which appears as 'the Dog' in the Vita and as 'the black hound of Arden' in Flores Historiarum, or noir chien de Ardene in the later French Chronicle. The other nicknames were not recorded until Edward III's reign, including 'Burst-Belly', boele-crevee, for Henry de Lacy, earl of Lincoln in the French Chronicle. Edward II's cousin Thomas, earl of Lancaster, was called 'the Churl' according to the English Brut, and 'the Fiddler' (vielers in the original) in the French Brut. The latter was said to have been inspired by Lancaster's appearance, because he was slim and tall (porceo quil est greles et de bel entaile).
The name Piers supposedly gave to Aymer de Valence, earl of Pembroke, 'Joseph the Jew', doesn't appear until Thomas Walsingham's chronicle at the end of the fourteenth century, around seventy years after Pembroke's death and a good eighty years after Gaveston's, and was said, in an echo of the Lancaster nickname, to have been inspired by Pembroke's appearance, pale and tall (eo quod pallidus esset et longus).
The most controversial of Piers' nicknames is given as filz a puteyne or 'whoreson' in the French Brut, and rendered as 'cuckold's bird' in the French Chronicle. This name is generally assumed to refer to Gilbert de Clare, earl of Gloucester, nephew of Edward II, because his mother Joan of Acre made a secret marriage in early 1297 to her late husband's squire, Ralph de Monthermer, against her father's wishes.
However, there are problems with this identification. Firstly, Gloucester's mother was also the mother of Gaveston's wife Margaret de Clare, and secondly and probably more importantly, Joan of Acre was Edward II's sister. I find it hard to believe that Gaveston would have maligned her so nastily, for Edward's sake if nothing else. And finally, the earl of Gloucester supported Gaveston for years, only giving him up in 1312 when Gaveston returned from his third, supposedly permanent, exile. Again, I find it hard to believe that Gloucester would have supported Gaveston for as long as he did if Gaveston had publicly called his mother a whore.
It's far more likely that the nickname 'whoreson' referred to Ralph de Monthermer, Gloucester's stepfather and Edward II's brother-in-law, earl of Gloucester in right of his wife Joan of Acre from 1297 to her death in April 1307. Ralph's parentage is obscure, but evidently he was illegitimate. In 1304, the writer of the Annals of London referred to him as 'the earl of Gloucester, called a bastard'.
In 1318, Ralph married Isabella, Lady Hastings, one of the sisters of Hugh Despenser the younger, without Edward II's permission. Edward fined them 1000 marks (666 pounds), but pardoned them and respited the debt in May 1321. ("Pardon to Ralph de Monte Hermerii and Isabella his wife, late the wife of John de Hastinges, tenant in chief, of the 1,000 marks by which the said Ralph made fine for the trespass committed by the said Isabella in marrying him without licence.")
In September 1324, Edward put Ralph and Isabella in charge of the household of his daughters Eleanor and Joan. Ralph had been part of Edward's family circle since Edward was twelve, and Lady Hastings was evidently a trustworthy, maternal sort: in December 1327, when Edward II's niece Elizabeth de Clare attended his funeral, she left her two young daughters in the care of Lady Hastings, despite her hatred of the lady's (dead) brother, Despenser.
Ralph died in January 1325, leaving four children by Joan of Acre, the eldest of whom, Mary, was married to the earl of Fife. Mary lived till after 1371, when she was well into her seventies, and Ralph's granddaughter Isabella, countess of Fife in her own right, married four times. Ralph's ultimate heir was his son Thomas's daughter Margaret de Monthermer, who lived to the mid-1390s. Margaret's son John Montacute succeeded as earl of Salisbury in 1397.
Pretty impressive descendants for an illegitimate squire, albeit one who persuaded two highborn ladies to marry him without the king's permission. Ralph de Monthermer must really have had something.