OK, so I’ve written the backstory for Marcus Jannus (main character and questgiver) and Valerius Artoria (Bandit leader):
Both were Captains in the Imperial Army and served under Titus Mede II during the Great War - most notably The Battle of Red Ring. Valerius had planned to sneak his family out of Cyrodiil and away from danger, but the Dominion invasion was swift and brutal, and his defenseless wife, son and daughter were all murdered by the Dominion forces while Valerius fought in another part of the province. After this, in his grief, Val became ruthless and obsessed with killing any and all Thalmor he could find, and by any means available. After the Battle of Red Ring, but while still serving in the Legion, Val decided to disobey strict orders and begin a series of covert assassinations of Thalmor officials and officers. Often taking several of his most trusted soldiers with him, and vowing to never recognize the White Gold Concordat he continued his brutal assaults for a few months. As a result of his actions and to appease certain Thalmor officials, Val was captured, given a dishonorable discharge from the Legion and stripped of his titles and any benefits he would ever receive for his service. He was basically ostracized and publicly ridiculed for his actions and thrown into a Legion prison. But the Thalmor feared executing him as they didn’t want to make a martyr out of him and possibly incite more insurrection, so they simply forced the Empire to lock him and his handful of men away forever.
However, after a period of time, resentment against the Thalmor and the Concordat grew and Marcus also became disillusioned with his own leadership - all the way up to Titus Mede II. He simply could not accept the concessions that were being made to the Thalmor. So, Marcus decided to retire from his service in the Legion as he wasn’t getting any younger. But before he retired, and unknown to Valerius, Marcus planned a means of escape for his old friend and his men. Valerius had saved Marcus’ life during The Battle of Red Ring, and Marcus never forgot what his old friend had done for him. Marcus’ years of service had accumulated him numerous favors throughout the ranks of the Legion. And on a dark, stormy night he was able to get one of his former soldiers, now a Lieutenant over the city prison, to quietly sneak the men out through an old, long forgotten passage out of the city.

Marcus and Val never actually saw one another during this escape, and Val had no idea whatsoever who and why someone helped him escape. But even though he had a new lease on life, his bitterness and hatred over the murder of his family still haunted him. And also knowing that he could not be seen in Cyrodiil again, he and his handful of men snuck their way into Skyrim. The years passed, and while there wasn’t necessarily a definitive hierarchy in their faction, Valerius became a quasi-leader of a group of Bandits he and his men helped form. Recognizing a prime opportunity to get themselves a new fort, they sprang into action after hearing of Helgen’s destruction and took over the place.
Meahwhile, Marcus who was still in what was left Cyrodiil, also heard rumors of a terrible dragon attack and that Helgen was indeed destroyed. The trading business he started after he retired had suffered for several years, and he longed to return to his childhood home. He felt the people in Skyrim – especially Helgen – needed him more than ever right now, so he left for Falcreath. Upon arriving at Falcreath, he heard the story of an individual who survived the attack and sent messengers to get word to this person to meet him in Falcreath. About the same time, Marcus also learned that someone only known as “Val” was heading up a group of bandits who had taken over the fort after Alduin’s attack.
Because the player had “inside” knowledge of the keep and Helgen in general, Marcus needs the player to return to Helgen through the caves and try to find out if this bandit leader is in fact his old friend Valerius as he suspects. If It is in fact his old friend Valerius, try to negotiate a truce with him on his behalf. Player will need to tell Val of Marcus’ plans to rebuild the town, and that he needs a partner and Captain of the Guard and that Marcus wants to meet with Val to discuss the matter.
Option 1 – Negotiate with Val: I will have Marcus give the player an item of some sort to prove to Val that that he/she were really sent by Marcus. It will most likely be the key that was used to help Val escape from prison. That way, Val will truly finally know who set him free, and remind him of the bond the two men shared on the battlefield so many years ago. Once Val agrees to meet with him, go get Marcus and follow him back to Helgen for the reunion of the two old friends.
Option 2 – Kill Val: If you’re a psychopath that doesn’t appreciate a heartwarming story of redemption, you can just kill Val and take his ring back to Marcus. This will guarantee that Bandits will constantly be attacking Helgen and wouldn’t be the advisable choice IMO. But it will be a choice nonetheless.
Thoughts anyone?