I think Underbeats Papyrus (aka Nico) would really look up to and aspire to be like Swap Sans. Possibly even Cross. They all have that older sibling responsibility thing going on (although Nico is actually the younger brother, taking care of his older sibling).
They all basically want to join the equivalent of the military or are/were already in it—Cross and Swap with the Royal Guards, and Nico with his AU’s equivalent called the Grand Orchestra Knights.
Even more literally, the GOK were formed during the human vs monsters war and it seems Maestro Gaster—Nico’s parent—either was involved in it during it’s creation in the war or created it themself seeing as they became a Commander (hidden under the alias Commander Shade.)
I would say that perhaps Maestro inspired Nico’s interest in joining the military, but given that they’re heavily traumatized by the war in multiple ways and it’s unclear what the present day purpose of the GOKs are, perhaps maestro is highly against their son joining.
Especially since, if I recall correctly, Maestro lost their mother and possibly their wife (Nico & Beats’ mother) during the war, and it was always emphasized that Nico takes a lot more after his mother.
But maybe Nico wants to join not only because he wants to prove himself and show he’s useful, but because he’s also a glass child—and he wants to get away from all the responsibilities his family puts on him with caring for Sans. It makes him feel horrible to think and feel that way, so the only person he’s told is his Uncle Grillby, but he can’t change how he feels.
I mean, in human years Beats is 16, meaning Nico is at least 12-14 in human years. So he plans and intends to join the GOK rather young, even for monsters of sound, it seems.
