FGrH F 128: (13) [lacuna] ...of silver, according to the ancestral custom; nor to associate with young fellows who drank freely, nor to remain at banquets till nightfall, nor to dine before the tenth hour, except at the house of Caesar or Philippus or Marcellus, his sister's husband, a man of sobriety and of the best Roman descent. Modesty [ aidos ], which one might assume was fitting for one of that age (for nature has assigned it an earlier place than other virtues) was apparent in his actions and continued during his whole life. Therefore Caesar made much of him and not as some think, entirely because of relationship. Some time before he had decided to adopt him, but fearing that elated at the hope of such good fortune, as those usually are who are brought up in wealth, he might become forgetful of virtue and depart form his accustomed mode of life, Caesar concealed his intention but he adopted him as son in his Will (for he had no male children of his own) and made him residuary legatee of his entire estate, after bequeathing one fourth of his property to friends and townsmen, as was afterwards known.
The title imperator dates back to the Roman Republic , when a victorious commander could be hailed as imperator in the field by his troops. The Senate could then award or withhold the extraordinary honour of a triumph ; the triumphal commander retained the title until the end of his magistracy .  In Roman tradition, the first triumph was that of Romulus, but the first attested recipient of the title imperator in a triumphal context is Aemilius Paulus in 189 BC.  It was a title held with great pride: Pompey was hailed imperator more than once, as was Sulla , but it was Julius Caesar who first used it permanently – according to Dio, this was a singular and excessive form of flattery granted by the Senate, passed to Caesar's adopted heir along with his name and virtually synonymous with it. 
Cancer creates a sense of urgency in the novel that wouldn’t exist otherwise. Because the characters are terminally ill, they view questions about life and its meaning very differently than their healthy counterparts, and their love is more meaningful to them than it might be to the average teenager. The reason is that death isn’t an abstraction to them. Hazel knows her cancer is terminal and that she will likely die before she becomes an adult. She also personally knows other kids who have died. Augustus has already had a girlfriend pass away from cancer. Because they know they likely have little time to live, they don’t have the luxury of figuring out what they believe about purpose and meaning over the course of several decades. The questions become immediate concerns that demand to be answered as soon as possible, whereas for healthy teenagers they’re more like philosophical questions. It also means that Hazel and Augustus realize their relationship may be the only significant one each has, even for Hazel who will likely live a few years, though perhaps not beyond that. As a result their love becomes that much more intense and meaningful.