Vectiam Bastaga was a Great Knight captain in charge of leading the baggage train during the Eclipse Expedition. Having previously worked as a merchant in her family business, Vectiam was able to use this administrative experience to efficiently coordinate the transportation of supplies. Due to the lack of combat that a position of escorting would receive, Vectiam's assigned squadron consisted mainly of inexperienced soldiers, much like Yunathrad's squadron, who she was friends with, and therefore was still rather vulnerable to attacks.

During the Eclipse Expedition, while entering Rovaltinny, Vectiam was with fellow captains Parean and Yunathrad, when they were attacked by a Crawler ambush targeting captains. During that ambush, Parean fell into a pit, but survived to crawl out. Unfortunately, Yunathrad was not as lucky and was dragged into a tunnel by a Crawler, presumably dragging her to her death. In an attempt to save her friend, Vectiam thrusted her halberd down to try and kill the Crawler, but in the panic, ended up penetrating Yunathrad's abdomen by accident, killing her. This severely affected Vectiam, who mourned the loss of her friend.

Subsequently, Vectiam continued to work on the logistical elements of the expedition. In the aftermath of the discovery of a razed Roval and the recovery of several Rovalian survivors, she tasked herself with the care of Amharia, an orphan discovered by Vince amongst the wreckage of an orphanage. While befriending her with casual conversation, Vectiam inadvertently discovered that Amharia was in fact an illegitimate child of the Rovalian King, which she later revealed to Vince when her supply column arrived at their newly-taken camp.

Despite having only occupied the base for a day, General Kirev immediately ordered the bulk of the Great Knights to continue advancing to the Rovalian fortress city of Duiost, leaving behind a substantial proportion of soldiers to guard the supply depot, which Vectiam at least agreed with.

Nevertheless, the march coincided with a major solar eclipse in the region, which allowed for a huge Chaos ambush on the column, targeting the weaker components of the Great Knights, including Vectiam's soldiers. While defending her position and becoming wounded by Dead projectiles in the process, she realised that Amharia had become distracted by the presence of her half-brother Negus, now a mutated Rovalian who was on the verge of shooting her. In spite of her incessant warnings, Amharia remained convinced that Negus could hear her, until Negus released the arrow (whether intentionally or not), which Vectiam intercepted with her own body. The arrow hit the weakened gap in her armour, instantly punching through to her lung.