~EMTs~
It was a sailor's ballad echoing through the tunnels, the tenor high and clear, that alerted him. Curious, he signaled to the others, and they diverted their course. The young man, when they found him, was in bad shape. He approached cautiously, ignoring the Leader's hissed warning, but the man greeted him like an old friend, obviously delusional. Closer, he could see that he was drunk with the pain, his leg twisted under a pile of collapsed tunnel wall.
The Leader cursed, but nodded. His brothers worked quickly to free him, while he applied the tourniquet, calling upon his limited knowledge of first aid and stifling his fear of failure. The man talked to them freely, assuming they were a hallucination brought on by the pain. He passed out somewhere half way to the hospital.
Haunted by a new awareness of his and his brothers' vulnerability, he relayed his fears to their father, who pondered, and then insisted they all learn emergency medicine. His brothers benefited more often than he would've liked from the lessons, but years later, when he heard a song echoing in the tunnels and spied a sewer worker with a limp, he breathed a silent thanks.
A/N: No episode reference this time, just my take on Don's tendency toward overthinking every situation, which leads, more often than not, to benefit for his family. :)
Many thanks to FairDrea and MelodyWinters for taking the time to beta. :)