only-one
Explanation
The Joke
A warrior declares: "If I cut off your head, I gain your powers!" The other character responds calmly: "My powers? You want my powers? Go nuts, bro." After the beheading occurs, the warrior begins experiencing the victim's "powers" — which turn out to be crippling self-doubt, social anxiety, and existential dread. He's shown overwhelmed by thoughts like "Did everyone hate me at dinner last night?" and "My friend who's more successful than me — does he think I'm a loser?" He ends up asking "What's happening?" as the disembodied head simply says: "Being me."
The Humor
The comic inverts the classic fantasy/action trope of gaining an enemy's powers through combat (as seen in Highlander and similar media). The victim doesn't resist because his "powers" are actually a curse — the relentless anxiety and self-consciousness that many people experience daily. The warrior expected super-strength or magic; instead he got intrusive thoughts and impostor syndrome.
The victim's calm willingness to give up his "powers" is the setup — it only makes sense in retrospect when we learn what those powers actually are. The joke resonates because it reframes common mental health struggles as something so burdensome that even a fearsome warrior is immediately incapacitated by them.
Broader Context
Weinersmith frequently finds humor in the gap between heroic/fantastical framing and mundane human reality. This comic uses the Highlander-style "there can be only one" power-absorption trope to make a surprisingly empathetic point about anxiety and mental health. The fact that the original character was functional while carrying all these thoughts — while the warrior is immediately overwhelmed — subtly suggests that people dealing with anxiety are tougher than they get credit for.