To unlock Boone’s companion quest, you must complete several different tasks that hurt the Legion in some meaningful way. Finishing these tasks gives you history points with Boone. You must obtain 5 or more history points to unlock his quest.

Tips before starting Boone’s quest:

• Have Boone with you. Unless you bring Boone with you while you finish these tasks, you won’t gain the required history points.
• It’s possible to lock yourself out of his quest. If you finish too many tasks without Boone, you may not be able to collect the required history points.
• The Legion will be hostile. Keep in mind that if a Legionnaire sees you with Boone in your party, they will immediately become hostile toward you.
• Speak to Boone periodically. As you gain more history points, you’ll unlock new dialogue options with Boone. Going through these is required to start the quest.

Task #1: Killing Vulpes Inculta

Vulpes Inculta is a legion Frumentarii that you interact with at multiple points throughout the game. Killing him while Boone is present will award 1 history point.

• The first time you can find Vulpes Inculta is when you first enter the town of Nipton, in front of the town hall. He’s nearly impossible to miss here, however, he is fully armed and accompanied by a posse of Legionaries. Killing him here may be difficult this early in the game. 

• The second time you encounter Vulpes is after finishing the main quest “Ring a Ding Ding” when you leave the Tops casino. Here, he is almost completely defenseless, unarmored, and without backup. Killing him here is the place to do so.

• The third and final time you encounter Vulpes is in Ceasar’s Tent in the Fort, right next to Ceasar. This is by far the most difficult place to kill Vulpes, but he’ll remain here for the entire playthrough. Come prepared. Note that to get to the fort, you must take a boat from Cottonwood Cove.

Task #2: Killing Ceasar

Ceasar, the leader of Ceasar’s Legion, is an incredibly difficult-to-kill enemy that can be found in his tent inside the Fort. He’s accompanied by Centurion Guards, Vulpes Inculta, and several other Legion members. Killing him, however, grants the player 2 history points with Boone.

Note that the Fort is only available after you finish the main story quest “Ring a Ding Ding” and that to get to the fort, you must take a boat from Cottonwood Cove.

If you want to take on Ceasar, your best bet is definitely going to be to equip medium-range weapons to deal with the Legionnaires outside his tent. Light Machine Guns, Assault Carabines, Brush Guns, and Marksman Carbines all work well for this purpose. 

Inside the tent, use either close-range weapons or melee/unarmed weapons. Shotguns, Combat Knives, Supersledges, and Power Fists all work quite well here.

Task #3: Finishing the “Booted” quest

This task awards 2 points.

The “Booted” quest can be started by speaking to Boxcars, an ex-powder ganger that can be found inside the Nipton general store. 

Boxcars will mention that there are two Powder Gangers that were taken by the Legion. Offer to save them. This will start the quest.

Next, proceed to the Legion Raid Camp, located northeast of Nipton. 

There, you’ll see several Legion soldiers who are holding the Powder Gangers captive. Kill the Legionnaires and untie the Powder Gangers. This will finish the quest and grant you the history points.

Task #4: Freeing the crucified soldiers in Nelson 

Finishing this task grants 2 history points.

In the center of the Legion-occupied town of Nelson, there are 3 crucified NCR soldiers. You can get one point by mercy killing them, however, it’s recommended that you kill the Legion soldiers guarding Nelson and free them instead. Doing this will award 2 points and some extra dialogue from Boone.

Quick tip for this area: Bring a long-range weapon. Due to the open nature of the town, as well as the fact that it’s surrounded by elevated ridges and hills, having a long-range weapon like a Sniper Rifle or an Anti-Materiel Rifle can make clearing this camp out a breeze.