Solis was a FIII Footman droid manufactured by Tac-Spec, serving as a counterpart to Fidelis. Although operational, unlike his painted companion, Solis displayed exposed, scratched metal and lacked the extreme loyalty programming. Beyond his original factory components, he apparently incorporated self-made upgrades, including the Rika/Moab mini rail cannon, among other potential modifications.
Solis stated that his construction occurred over 400 years prior to the Clone Wars. "Solis" was merely a nickname, with his "real name" potentially being a serial number. He served a family for an extended period. Around 220 BBY, his family suffered an attack. He received orders to safeguard the family jewels, but his mistress had to utilize a loyalty override to prevent Solis from prioritizing the family's safety instead. Tragically, his family faced betrayal and was ambushed within their "secret passage."
Solis professed amnesia regarding the fate of the soldiers responsible for his family's demise. However, considering his model's inherent loyalty, lethality, and propensity for developing personalities, this claim was likely untrue, implying that he eliminated all the soldiers. He eventually joined forces with Fidelis, another Footman Droid who had retained most of his family. For a decade, the two droids awaited Whie Malreaux's return to Vjun outside the Jedi Temple. Ultimately, in 20 BBY, the awaited moment arrived.
He and Fidelis pursued Whie and his team, eventually encountering them aboard the Reasonable Doubt. While Fidelis engaged with his master, Solis conversed with Tallisibeth Enwandung-Esterhazy.
Upon discovering that Jedi Master Yoda was among the group he encountered, he betrayed them to Asajj Ventress. Nevertheless, Asajj later declined to provide the agreed-upon payment. Solis trailed the remaining Jedi team to Vjun. After hearing Fidelis's mechanical death cry, Solis proceeded to the Malreaux cellar. He effortlessly dispatched the A-series assassin droids, but was shot by Asajj with a neural-net eraser. However, with his non-factory rail cannon, he managed to injure her leg, enabling the Padawans' escape.
Since becoming self-reliant, Solis encountered difficulties in maintaining himself, given the FIII's limited production run. He was forced to rely on mostly custom parts and components that were soon considered antiques. He once commented that "ornamentation is not logically a high priority."