In 358 -359, Lucillianus and Procopius formed the second embassy sent by Constantius to Shapur II, negotiating terms of peace and returning without results. Lucillianus later attempted to counter the advance of Julian the Apostate and his forces against Constantius. He was defeated however and was dismissed from the Roman army when Julian rose to the throne. 
Ammianus and Zosimus give two slightly different accounts on the role of the imperial father-in-law in the brief reign of Jovian. Lucillianus was reinstated and received orders to move to Mediolanum. In secret, Jovianus also asked him to "take with him some men selected for their tried vigour and loyalty, with the view of making use of their support as the condition of affairs might suggest". 
The return of Lucillianus to action would result in his death sometime later. He was killed by his own men after a false rumour indicated that Julian was still alive. 
According to Zosimus, Lucillianus was murdered for being the bearer of the bad news about the death of Julian.  The two accounts differ in the location of the death, Rheims or Sirmium, and on which units were responsible. Ammianus leaves it vague while Zosimus points at specific units.
Charito married Jovian, a son of Varronianus. Her father-in-law was tribune of the Jovians and comes domesticorum. Varronianus retired into private life during the reign of Julian. Jovian had also pursued a military career, serving as primicerius domesticorum under Julian. They had at least one son, also named Varronianus.Philostorgius claims that Varronianus was one of two sons. The other son is not named. However this brief mention is the only source mentioning or suggesting the existence of a second son.
On 26 June 363, Julian was mortally wounded in the Battle of Samarra. He died a few hours following the end of the conflict. He was childless and had never designated an heir. On 27 June, the remaining officers of the campaign proceeded to elect a new emperor, selecting Jovian for unclear reasons. Charito became the new empress.
The body of Jovian was sent to Constantinople, to be interred with his predecessors, and the sad procession was met on the road by his wife Charito, the daughter of Count Lucillian; who still wept the recent death of her father, and was hastening to dry her tears in the embraces of an Imperial husband. Her disappointment and grief were imbittered by the anxiety of maternal tenderness. Six weeks before the death of Jovian, his infant son had been placed in the curule chair, adorned with the title of Nobilissimus, and the vain ensigns of the consulship. Unconscious of his fortune, the royal youth, who, from his grandfather, assumed the name of Varronian, was reminded only by the jealousy of the government, that he was the son of an emperor. Sixteen years afterwards he was still alive, but he had already been deprived of an eye; and his afflicted mother expected every hour, that the innocent victim would be torn from her arms, to appease, with his blood, the suspicions of the reigning prince."
The reference to Varronianus being half-blind comes from the "Homilies on Philippians" by John Chrysostom. "Another again, his successor, was destroyed by noxious drugs, and his cup was to him no longer drink, but death. And his son had an eye put out, from fear of what was to follow, though he had done no wrong." Louis-Sébastien Le Nain de Tillemont was the first to identify the poisoned emperor with Jovian and the son with Varronianus. Gibbon and others have followed this interpretation. Tillemont assumed that Varronianus was eventually executed but there is no ancient or medieval text supporting the notion.
The reference to the fate of Charito comes from the "Letter to a Young Widow" by John Chrysostom, written c. 380.
"Now passing over ancient times, of those who have reigned in our own generation, nine in all, only two have ended their life by a natural death; and of the others one was slain by a usurper, one in battle, one by a conspiracy of his household guards, one by the very man who elected him, and invested him with the purple, and of their wives some, as it is reported, perished by poison, others died of mere sorrow; while of those who still survive one, who has an orphan son, is trembling with alarm lest any of those who are in power dreading what may happen in the future should destroy him, another has reluctantly yielded to much entreaty to return from the exile into which she had been driven by him who held the chief power."
The original passage is quite vague in not actually naming the emperors or empresses mentioned. The interpretation given by Gibbon and others identifies the two emperors who died of natural causes with Constantine I and Constantius II. The one slain by a usurper was Constans, assassinated by orders of rival emperor Magnentius. The one killed in battle is thought to be Constantine II. The one assassinated by his guards was Jovian, since Chrysostom expressed the same belief in another of his texts. The one killed by the man who elevated him to the purple was Constantius Gallus, created Caesar by Constantius II and later executed by orders of the same emperor. The empress trembling for the life of her son is thought to be Charito. The one returning from exile is tentatively identified with Marina Severa, first wife of Valentinian I and mother of Gratian. However the identification is very doubtful in this case as her life following her divorce is not recorded by other sources.
Bleterie considered Charito to have been a Christian and comments "no one had ever more need of the solid consolations which Christianity alone can give".
^ abSelect Works of Emperor Julian (1786), English anthology including a translation of the History of Jovian, p. 364. See also de La Bléterie, J. P., Histoire de Jovien, 1740, i. p. 1-238; and Garland, Lynda, Byzantine Empresses: Women and Power in Byzantium, AD 527-1204, Psychology Press, 1999, p. 229. ISBN 978-0415146883.
^Timothy Barnes, "Ammianus Marcellinus and the Representation of Historical Reality" (1998), page 123
^N. J. E. Austin and N. B. Rankov, "Exploratio:Military and Political Intelligence in the Roman World from the Second Punic War to the Battle of Adrianople" (1998), page 224
^According to Ammianus:"On these very same days Prosper, Spectatus, and Eustathius, who had been sent as envoys to the Persians (as we have shown above), approached the king on his return to Ctesiphon, bearing letters and gifts from the emperor, and demanded peace with no change in the present status. Mindful of the emperor's instructions, they sacrificed no whit of the advantage and majesty of Rome, insisting that a treaty of friendship ought to be established with the condition that no move should be made to disturb the position of Armenia or Mesopotamia. Having therefore tarried there for a long time, since they saw that the king was most obstinately hardened against accepting peace, unless the dominion over those regions should be made over to him, they returned without fulfilling their mission. Afterwards Count Lucillianus was despatched, together with Procopius, at that time state secretary, to accomplish the self-same thing with like insistence on the conditions; the latter afterwards, bound as it were by a knot of stern necessity, rose in revolution. - The Roman History of Ammianus Marcellinus, vol. 1, Book 17, chapter 14. 1935 translation; "When our scouts had returned there, we found in the scabbard of a sword a parchment written in cipher, which had been brought to us by order of Procopius, who, as I said before, had previously been sent as an envoy to the Persians with Count Lucillianus. In this, with intentional obscurity, for fear that, if the bearers were taken and the meaning of the message known, most disastrous consequences would follow, he gave the following message: Now that the envoys of the Greeks have been sent far away and perhaps are to be killed, that aged king, not content with Hellespontus, will bridge the Granicus and the Rhyndacus and come to invade Asia with many nations. He is naturally passionate and very cruel, and he has as an instigator and abetter the successor of the former Roman emperor Hadrian;unless Greece takes heed, it is all over with her and her dirge chanted." ; "This writing meant that the king of the Persians had crossed the rivers Anzaba and Tigris, and, urged on by Antoninus, aspired to the rule of the entire Orient. When it had been read, with the greatest difficulty because of its excessive ambiguity, a sagacious plan was formed." - The Roman History of Ammianus Marcellinus, vol. 1, Book 18, chapter 6. 1935 translation
^According to Ammianus:"Rumour, which with a thousand tongues, as men say, strangely exaggerates the truth, spread herself abroad with many reports throughout all Illyricum, saying that Julian, after overthrowing a great number of kings and nations in Gaul, was on the way with a numerous army and puffed up by sundry successes. Alarmed by this news, the pretorian prefect Taurus speedily retreated, as if avoiding a foreign enemy, and using the rapid changes of the public courier-service, he crossed the Julian Alps, at the same stroke taking away with him Florentius, who was also prefect. Nonetheless, Count Lucillianus, who then commanded the troops stationed in those regions, with headquarters at Sirmium, having some slight intelligence of Julian's move, gathered together such forces as regard for speedy action allowed to be summoned from the neighbouring stations and planned to resist him when he should arrive. But Julian, like a meteor or a blazing dart, hastened with winged speed to his goal; and when he had come to Bononea, distant nineteen miles from Sirmium, as the moon was waning and therefore making dark the greater part of the night, he unexpectedly landed, and at once sent Dagalaifus with a light-armed force to summon Lucillianus, and if he tried to resist, to bring him by force. The prefect was still asleep, and when he was awakened by the noise and confusion and saw himself surrounded by a ring of strangers, he understood the situation and, overcome with fear on hearing the emperor's name, obeyed his command, though most unwillingly. So the commander of the cavalry, just now so haughty and self-confident, following another's behest, was set upon the first horse that could be found and brought before the emperor like a base captive, scarcely keeping his wits through terror. But when at first sight of Julian he saw that the opportunity was given him of bowing down to the purple, taking heart at last and no longer in fear for his life, he said: "Incautiously and rashly, my Emperor, you have trusted yourself with a few followers to another's territory." To which Julian replied with a bitter smile: "Reserve these wise words for Constantius, for I have offered you the emblem of imperial majesty, not as to a counsellor, but that you might cease to fear." - The Roman History of Ammianus Marcellinus, vol. 2, Book 21, chapter 9. 1940 translation
^"Procopius, a state-secretary, and the military tribune Memoridus were sent to the lands of Illyricum and Gaul, to announce the death of Julianus, and the elevation of Jovian (after Julianus's decease) to Augustan rank. To them the emperor had also given instructions to hand his father-in‑law Lucillianus, who after his dismissal from the army had retired to a life of leisure and was then living at Sirmium, the commission as commander of the cavalry and infantry which he had delivered to them, and urge him to hasten to Milan, in order to attend to any difficulties there, or if (as was now rather to be feared) any new dangers should arise, to resist them. To these instructions the emperor had added a secret letter, in which he also directed Lucillianus to take with him some men selected for their tried vigour and loyalty, with the view of making use of their support as the condition of affairs might suggest. And he took the prudent step of appointing Malarichus, who also was even then living in Italy in a private capacity, as successor to Jovinus, commander of the cavalry in Gaul, sending him the insignia of that rank. Thereby he aimed at a double advantage: first, in getting rid of a general of distinguished service and therefore an object of suspicion; and, second, the hope that a man of slight expectations, when raised to a high rank, might show great zeal in supporting the position of his benefactor, which was still uncertain. Also the men who were commissioned to carry out these plans were ordered to set the course of events in a favourable light, and wherever they went, to agree with each other in spreading the report that the Parthian campaign had been brought to a successful end. They were to hasten their journey by adding night to day, to put into the hands of the governors and the military commanders of the provinces the messages of the new emperor, to secretly sound the sentiments of all of them, and to return steadily with their replies, in order that as soon as it was learned how matters stood in the distant provinces, timely and careful plans might be made for safeguarding the imperial power." - The Roman History of Ammianus Marcellinus, vol. 2, Book 25, chapter 8. 1940 translation
^"After this the emperor left Tarsus, and making long marches arrived at Tyana, a town of Cappadocia, where on their return the secretary Procopius and the tribune Memoridus met him. They gave him an account of their missions, beginning (as order demanded) with the entry of Lucillianus with the tribunes Seniauchus and Valentinianus, whom he had taken with him, into Mediolanum; but on learning that Malarichus had refused to accept the position he had gone at full speed to Rheims. Then, as if that nation were in profound peace, he ran off the track (as the saying is), and quite out of season, since everything was not yet secure, devoted his attention to examining the accounts of a former actuary. This man, being conscious of deceit and wrongdoing, fled for refuge to the army and falsely asserted that Julianus was still alive and that a man of no distinction had raised a rebellion; in consequence of his falsehoods a veritable storm broke out among the soldiery, and Lucillianus and Seniauchus were killed. For Valentinianus, who was shortly afterwards emperor, in terror and not knowing where to turn, was safely gotten out of the way by Primitivus, his guest-friend. This sad news was followed by another message, this time a happy one, namely, that soldiers sent by Jovinus, heads of the divisions, as camp parlance termed them, were on the way, reporting that the Gallic army embraced with favour the rule of Jovian - The Roman History of Ammianus Marcellinus, vol. 2, Book 25, chapter 10. 1940 translation
^"Jovian now turning his attention to the affairs of government, made various arrangements, and sent Lucilianus his father-in-law, Procopius, and Valentinian, who was afterwards emperor, to the armies in Pannonia, to inform them of the death of Julian, and of his being chosen emperor. The Batavians who were at Sirmium, and were left there for its protection, as soon as they received the news, put to death Lucilianus who brought such unwelcome intelligence, without regard to his relationship to the emperor. Such was the respect they had to Jovian's relations, that Valentinian himself only escaped from the death they intended to inflict on him." Zosimus, New History, Book 3. 1814 translation.
^According to Ammianus: "It was said that his father, Varronianus, learned what would happen long beforehand from the suggestion of a dream, and trusted the information to two of his confidential friends, adding the remark that the consular robe would be conferred also on himself. But although one prophecy was fulfilled, he could not attain the other prediction. For after learning of the elevation of his son, he was overtaken by death before seeing him again. And since it was foretold to the old man in a dream that the highest magistracy awaited one of that name, his grandson Varronianus, then still a child, was ... made consul together with his father Jovianus." - The Roman History of Ammianus Marcellinus, vol. 2, Book 25, chapter 10. 1940 translation
^Ammianus records:"When the emperor had entered Ancyra, after the necessary arrangements for his procession had been made, so far as the conditions allowed, he assumed the consulship, taking as his colleague in the office his son Varronianus, who was still a small child; and his crying and obstinate resistance to being carried, as usual, on the curule chair, were an omen of what presently occurred."The Roman History of Ammianus Marcellinus, vol. 2, Book 25, chapter 10. 1940 translation. The historian interprets the crying consul as an ill omen, preceding the early death of Jovian.