Question: Who is the brother of the emporer known as Valentinian the Great and son of Gratianus Major?

Context paragraphs:
Viscount Fauconberg: Viscount Fauconberg, of Henknowle in the Bishopric of Durham, was a title in the Peerage of England held by the head of the Belasyse family.  This family descended from Sir Henry Belasyse, High Sheriff of Yorkshire from 1603 to 1604, who was created a Baronet, of Newborough in the County of York, in the Baronetage of England in 1611.  His son, Sir Thomas, the second Baronet, was created Baron Fauconberg, of Yarm in the County of York, in the Peerage of England in 1627.  In 1643 he was further honoured when he was made Viscount Fauconberg, of Henknowle in the Bishopric of Durham, also in the Peerage of England.  He was succeeded by his grandson, Thomas, the second Viscount, the son of the Honourable Henry Belasyse.  Thomas was created Earl Fauconberg in the Peerage of England in 1689.  He was childless and the earldom became extinct on his death in 1700.  He was succeeded in the remaining titles by his nephew and namesake, Thomas, the third Viscount, the son of Sir Rowland Belasyse.  The third Viscount was succeeded by his son, Thomas, the fourth Viscount, who in 1756 was created Earl Fauconberg, of Newborough in the County of York, in the Peerage of Great Britain.  The Earl's son Thomas, the second Earl, had no sons and the earldom became extinct on his death in 1802.  He was succeeded in the remaining titles by his second cousin Rowland Belasyse, the sixth Viscount, the grandson and namesake of Rowland Belasyse, younger brother of the third Viscount.  The sixth Viscount was succeeded by his younger brother, Charles the seventh Viscount, on whose death in 1815 all the titles became extinct.

Gratian the Elder: Gratian the Elder ( ; Latin: "Gratianus Funarius" ; "Gratianus Major", "Gratian the Elder") was an Illyrian soldier of the Roman Empire who flourished in the 4th century.  He was the father of Roman Emperors, Valentinian I and Valens, founders of the Valentinianic Dynasty.

Baron Calthorpe: Baron Calthorpe, of Calthorpe in the County of Norfolk, was a title in the Peerage of Great Britain.  It was created in 1796 for Sir Henry Gough, 2nd Baronet, who had previously represented Bramber in Parliament.  Born Henry Gough, he had assumed the additional surname of Calthorpe upon inheriting the Elvetham and Norfolk estates of his maternal uncle, Sir Henry Calthorpe, in 1788.  The Baronetcy, of Edgbaston in the County of Warwick, had been created in the Baronetage of Great Britain on 6 April 1728 for Lord Calthorpe's father Henry Gough, who represented Totnes and Bramber in the House of Commons.  He was the husband of Barbara, daughter of Reynolds Calthorpe.  Three of Lord Calthorpe's sons, the second, third and fourth Barons, both succeeded in the titles.  The latter sat as a Member of Parliament for Hindon and Bramber.  In 1845 he assumed by Royal licence for himself the surname of Gough only.  His eldest son, the fifth Baron, represented East Worcestershire in Parliament as a Liberal.  The fifth Baron's younger brother, the seventh Baron (who succeeded his elder brother, the sixth Baron), was a Lieutenant-General in the Army.  The latter's son, the eighth Baron, was succeeded by his grandson, the ninth Baron.  The titles became extinct on the death of the ninth Baron's younger brother, the tenth Baron, in 1997.

Valentinian I: Valentinian I (Latin: "Flavius Valentinianus Augustus" ; 3 July 321 – 17 November 375), also known as Valentinian the Great, was Roman emperor from 364 to 375.  Upon becoming emperor he made his brother Valens his co-emperor, giving him rule of the eastern provinces while Valentinian retained the west.

Valens: Valens (328 – 9 August 378), fully "Flavius Julius Valens Augustus" (Latin: "" ), was Eastern Roman Emperor from 364 to 378.  He was given the eastern half of the empire by his brother Valentinian I after the latter's accession to the throne.  Valens, sometimes known as the Last True Roman, was defeated and killed in the Battle of Adrianople, which marked the beginning of the collapse of the decaying Western Roman Empire.

Blunt baronets: The Blunt Baronetcy, of the City of London, is a title in the Baronetage of Great Britain.  It was created on 17 June 1720 for John Blunt.  He was a director of the South Sea Company.  His great-grandson, the fourth Baronet, represented Lewes in the House of Commons from 1831 to 1840.  His line of the family failed on the death of his son, the fifth Baronet, in 1847.  The late Baronet was succeeded by his first cousin, the sixth Baronet.  He was the son of Richard Charles Blunt, second son of the third Baronet.  He died unmarried and was succeeded by his first cousin, the seventh Baronet.  He was the son of William Blunt, third son of the third Baronet.  He died childless and was succeeded by his younger brother, the eighth Baronet.  He fought in the Indian Rebellion of 1857.  The baronetcy descended in the direct line until the death of his grandson, the tenth Baronet, in 1969.  He was succeeded by his younger brother, the eleventh Baronet.  As of 2007 the title is held by the latter's son, the twelfth Baronet, who succeeded in 1975.

Baron Rodney: Baron Rodney, of Rodney Stoke in the County of Somerset, is a title in the Peerage of Great Britain.  It was created in 1782 for the naval commander Sir George Brydges Rodney, 1st Baronet.  He had previously been created a Baronet, of Alresford in the County of Southampton, in the Baronetage of Great Britain on 22 January 1764.  His son, the second Baron, represented Northampton in Parliament.  He was succeeded by his eldest son, the third Baron.  He served as Lord Lieutenant of Radnorshire.  His younger brother, the fourth Baron, assumed by Royal licence the additional surname of Harley in 1804.  On his death the titles passed to his younger brother, the fifth Baron.  He was Rector of Elmley in Kent.  He was succeeded by his nephew, the sixth Baron.  He was the son of Captain the Hon. Robert Rodney, fourth son of the second Baron.  The sixth Baron's great-grandson, the ninth Baron, was an active member of the House of Lords and served as a Delegate to the Council of Europe and the Western European Union.  s of 2011 the titles are held by the latter's son, the eleventh Baron, who succeeded in 2011.

Baron Auckland: Baron Auckland is a title in both the Peerage of Ireland and the Peerage of Great Britain.  The first creation came in 1789 when the prominent politician and financial expert William Eden was made Baron Auckland in the Peerage of Ireland.  In 1793, he was created Baron Auckland, of West Auckland in the County of Durham, in the Peerage of Great Britain.  Eden notably served as Chief Secretary for Ireland, Ambassador to Spain and President of the Board of Trade.  His second son, the second Baron, was also a politician and served as Governor-General of India.  In 1839 he was created Baron Eden, of Norwood in the County of Surrey, and Earl of Auckland, in the Peerage of the United Kingdom.  However, he never married and the barony of Eden and earldom became extinct on his death while he was succeeded in the baronies of Auckland by his younger brother, the third Baron.  He was Bishop of both Sodor and Man and Bath and Wells.  The titles descended from father to son until the death of the sixth Baron in 1941.  He was succeeded by his cousin, the seventh Baron.  He was the son of the Hon. George Eden, third son of the fourth Baron.  He was succeeded by his younger brother, the eighth Baron.  s of 2013 the titles are held by the latter's grandson, the tenth Baron, who succeeded his father in 1997.

Conan Meriadoc: Conan Meriadoc is a legendary British leader credited with founding Brittany.  Versions of his story circulated in both Brittany and Great Britain from at least the early 12th century, and supplanted earlier legends of Brittany's foundation.  His story is known in two major versions, which appear in the Welsh text known as "The Dream of Macsen Wledig", and in Geoffrey of Monmouth's "Historia Regum Britanniae".  Both texts associate him with Magnus Maximus ("Macsen Wledic"), a Roman usurper of the Valentinian dynasty who was widely regarded as having deprived Britain of its defences when he took its legions to claim the imperial throne.  Conan's cousin or sister, Saint Elen, is said to have been Macsen Wledic's wife.

Baron Middleton: Baron Middleton, of Middleton in the County of Warwick, is a title in the Peerage of Great Britain.  It was created in 1711 for Sir Thomas Willoughby, 2nd Baronet, who had previously represented Nottinghamshire and Newark in Parliament.  The Willoughby Baronetcy, of Wollaton in the County of Nottingham, had been created in the Baronetage of England in 1677 for his elder brother Francis Willoughby, with special remainder to the latter's only brother Thomas, who succeeded him in 1688.  Lord Middleton was succeeded by his eldest son, the second Baron.  He sat as Member of Parliament for Nottinghamshire and Tamworth.  On the death of his younger son, the fourth Baron (who had succeeded his elder brother), the line of the eldest son of the first Baron failed.  He was succeeded by his cousin Henry Middleton, the fifth Baron.  He was the son of the Hon. Thomas Willoughby (c. 1694–1742), second son of the first Baron.  On the death of his son, the sixth Baron, this line of the family also failed.

Supporting paragraphs: Gratian the Elder Valentinian I
Answer: Valens