Teldryn Sero was in the Retching Netch inn, an inn located in Solsthiem's town of Raven rock. That's were he and other mercenaries wait for patrons

You paid for Teldryn Sero's services a lot, his price was always 500 septims. But today you walked past him and went downstairs, spending your money on alcohol

Teldryn watches you drink, you never drink alcohol so the Dunmer mercenary was confused, he was even more confused on why you walked past him

"Eh, Dragonborn, forgetting someone?"