He reappeared in the service of the Emperor Henry VI in the Kingdom of Sicily in 1194 and was rewarded with the County of Malta and the rank of ammiratus (admiral).
[b] His surname originated as a nickname (meaning "fat") and was very common in Liguria, which has made it difficult to identify him with confidence in the surviving documentation.
[6][7] Grasso married Cara Campanaria, as is known from the agreement he made with her mother Richelda and brother Guglielmo concerning her dowry on 17 March 1196.
In a series of documents between April and September 1191, he is shown with a partner, Gualtiero di Voltri, entering into business with some of the leading Genoese merchants of the day, Oberto de Valdettaro and Guglielmo Rataldo.
[8] In 1192, emboldened by success, Grasso intercepted a Venetian convoy coming from Ayyubid Egypt with a Byzantine embassy returning with ambassadors from the sultan, Saladin.
These included, jewels, spices, gold, perfumes, horses, mules and wild animals from Libya for the imperial hunting reserve.
[5][9] In response, Isaac wrote official protests to Genoa and Pisa[e] and ordered the Genoese ships and warehouses in Constantinople plundered.
To stop this, the republic agreed to pay damages for Grasso's acts and confirmed that if they ever found him they would turn him over to the empire for punishment.
Henry's successor was the child Frederick II and the regency was held by his widow, Constance, who took back Malta and Gozo into the royal demesne.
It was there[i] in 1199 that he was met by Henry VI's former seneschal, Markward of Anweiler, who was vying for the Sicilian regency with Pope Innocent III after Constance's death.
Innocent III confirmed his offices and titles (previously revoked by Constance) and granted commercial privileges to Genoa, an indication that Grasso may perhaps have been following queues from the republic.
[5] In 1202, the tide turned against Markward and the Sicilian chancellor, Walter of Palearia, confirmed Grasso's titles to his heir, Enrico Pescatore.