Thank you for your comment, and your question. Both these men are strangers in an uncertain situation far from home. While Parcival fights his nature to appear as a proper knight, Ted leans into his nature as something of a crutch. Whatever the reason, he makes the opposite blunder of Parcival: rather than holding it all back for appearances, he lets it all out, appearances be damned.
Whereas Parcival would have been able to heal the Grail King with his nature, try as he might, Ted will not be able to do the same with Rebecca. Maybe there was no “What ails thee?” equivalent in Ted’s case. Not to spoil the plot too much, but Rebecca does eventually bend. Ted himself doesn’t heal Rebecca, though his nature does show her there’s another way to live; she’s responsible for healing herself.