Prefer to go it alone? With the Lone Wanderer perk, you'll take less damage and be able to carry more equipment when you adventure without a companion or dog.”— Fallout 4 loading screen hints
When traveling without a companion, the Sole Survivor gets a few benefits. With the first rank, they take 15% less damage and can carry 50 more pounds. The second rank increases these to 30% less damage and 100 extra pounds when without a companion. The third and final rank causes the Sole Survivor to do 25% extra damage when traveling without a companion.
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