The Underworld, as you may have heard, is a sort of haven for ghouls in the DC Wasteland. Super Mutants don't bother the ghouls and so unintentionally serve as a barrier between the city of ghouls and the bigoted "smoothskins" above. A ghoul trader named Quinn happened to be returning to The Underworld shortly after 101's collapse. Quinn was one of the few ghouls with no reason to be wary of humans (having met plenty who were friendly towards him) and took pity on 101, carrying her in to Dr Barrows for treatment. Dr Barrows diagnosed the unconscious 101 with "exhaustion" and told Quinn to just leave her on one of the cots to recover.
101 finally woke several days later. She was grateful for the help and gained permission to stay in Underworld as long as she liked, providing she didn't cause any trouble. That certainly seemed easy enough. In fact, the residents of Underworld were, for the most part, fairly friendly. 101 wanted to thank Quinn for bringing her in, but he had already left for his trade route. She decided to hang around for a while and helped out by cleaning up around Carol's Place, Underworld's hotel, in exchange for a place to sleep while she got herself together. It was during this time that 101 ran into a shady fellow named Ahzrukhal and learned his dirty little secret.
Apparently Ahzrukhal's "body guard" was, in fact, a slave. Brainwashed into blindly serving whomever held his contract. That didn't seem right at all. 101 offered Ahzrukhal 2000caps for Charon's contract; an offer that proved to be irresistible. Ahzrukhal handed over the contract and 101 informed Charon of his new employment conditions. 101 could swear she saw a glint in his eye as he excused himself for a moment.
Brainwashed into compliance or not, Charon obviously wasn't happy with his previous employer. He turned to 101 and said, "We can go now". Yes, perhaps they should. Nobody appeared overly concerned by the loss of Ahzrukhal, but it still seemed a good idea for them to get away from Underworld for a while. As they made their way out of the DC Ruins and out into the Wasteland 101 took a chance and asked Charon if there was anywhere he'd like to go. "Wherever you tell me". Okay, then. As she consulted her Pip-boy's map 101 remembered Agatha and her Stradivarius. According to the information she had retrieved from Vault-tec, Vault 92 was situated far to the north. She asked Charon how he felt about visiting Vault 92. His reply was, "I'll follow you wherever you go". That would be almost romantic if not for the contract...
That's how "The Angel of the Wasteland" ended up travelling with her first, and some say 'favorite', ghoul companion - Charon. He was a tremendous asset with a keen eye and unbelievable accuracy; even if he wasn't much for conversation. It was an unusual beginning, as far as relationships go. 101 found she liked having company and talked almost non-stop. Her questions often received non-committal or grunted responses, but she kept at it anyway. As the pair headed north towards Vault 92 she had recounted nearly everything she could remember while learning nothing about her companion in return. That was okay, 101 was sure she'd get him to open up eventually. In the meantime she was grateful having someone to listen and watch her back. Besides, their adventure had only just begun.