As the days passed and Chara and Frisk's friendship deepened, Sans found himself increasingly consumed by a gnawing sense of jealousy that threatened to consume him from the inside out. It wasn't that Sans begrudged Frisk their friendship with Chara – far from it – but there was something about the easy camaraderie between them that left Sans feeling like he was somehow lacking. Try as he might to brush off his feelings as nothing more than a passing fancy, Sans couldn't shake the nagging sense of inadequacy that gnawed at him, a festering wound that refused to heal no matter how hard he tried to ignore it.
It wasn't that Sans didn't have friends of his own – he did, of course – but there was something about the bond between Chara and Frisk that left him feeling like an outsider, a third wheel in a relationship that he didn't fully understand. He tried to rationalize his feelings, to convince himself that there was nothing to be concerned about, that Chara was simply a friend like any other, but deep down, Sans knew that his jealousy ran deeper than that. There was a part of him that longed for the kind of connection that Chara and Frisk shared, a sense of belonging and companionship that seemed to elude him no matter how hard he tried to grasp it.
As Sans watched Chara and Frisk interact, their laughter ringing out like a melody in the dimly lit corridors of the Underground, he couldn't help but feel a pang of longing gnawing at him, a desire to be a part of something greater than himself. He wanted to be the one to make Chara smile, to share inside jokes and quiet moments of companionship, but as he watched them grow closer with each passing day, Sans couldn't shake the feeling that he was somehow being left behind, a bystander to a friendship that he couldn't help but envy.
