All three are (or were) soldiers belonging to the Russian Aerospace Forces. They belong to the same unit and crew the Mi-24P-2M "Hind-E" attack helicopter.
Dmitry and Alexei's father was once a pilot in the Soviet and then Russian Air Forces, and since childhood, the two dreamed of becoming pilots like their father. One day, when they were in middle school, their father took them to an air show. What caught their eye was the Mi-24, the very aircraft they would later fly. The moment they saw it, their eyes widened. Dmitry, who until then had hated studying, fooled around, and was a delinquent, suddenly began to focus on his studies, eventually improving enough to stand shoulder-to-shoulder with Alexei.
After that, they both entered military academy at a young age, graduated with extremely outstanding results, and subsequently achieved the rank of Captain while still in their early 20s. This was an extremely rapid promotion, and rumors flew that their high-ranking father might have been involved. In any case, they had achieved their long-held dream.
Now, as for Isaac, he was an extremely ordinary Russian. He lost his parents in an accident right after he was born and was sent to live with his maternal grandmother along with his older brother, where he was raised with plenty of love. However, the family was poor, and when his brother fell critically ill, the situation became desperate. Needing money at all costs, Isaac saw a recruitment poster and immediately ran to the recruitment center. After enlisting, he endured the harsh military life, becoming a mechanic and eventually a flight engineer. He was on the verge of becoming a pilot and earning enough to support his family.
...However, one day, Dmitry and Alexei got into trouble with a superior officer and ended up killing him. They immediately kidnapped the nearby flight engineer, Isaac, as a hostage, boarded their aircraft, and attempted to flee the country—with no specific destination in mind. They were immediately pursued by fighter jets. Just as they thought they were about to be shot down by a missile, a blinding light enveloped their aircraft. When they opened their eyes next, they had landed in a grassy field.
Thus, they arrived in this new world.
Since then, the three of them (only two of whom have human rights) operate as "Surkov Transport," using their Hind for transporting goods and people, assassinations, illegal shipping, and noise harassment.