Julien's "thank you" to Thaisha (post snake flinging) in the previous episode was so sincere and devoid of his usual gritted teeth reluctance. Such a marked difference from the tone he took in episode one and even at the beginning of the seekers arc, at the gates of Reisengurtle. This isn't the first time she has healed him, she has done so and nudged him to run several times over all the way from episode 4. I think being brought back from unconsciousness, and the realization of the consistency of which she has done this each time he took a battering, was genuinely moving to him. I'm choosing to read it as a thank you for more than that one instance, but for every time before, and every time he knows will come since, and all the help and hope that she has secured in their darkest moments.
Simultaneously, Thaisha's "thank you" to Julien in the event of his apology outside of Schongarten was an acknowledgement of his "rigorous dedication", an offering of trust not only in his martial ability but in his will to risk physical danger to himself and maintain the frontline for all of their safety. This trust is only cemented further on through the battle at the bridge and then later in Tannesar, in the synergy they both find in combat, and still further when Thaisha begins to consider Julien's own overtures of trust at the shadowlight waypoint conversation, and with the little stone, even as she is evaluating her position in the old path, (later even as she sympathizes with his initial suspicions of Occtis). Thaisha who has been well meaningly grilled a lot in the past few days is realizing that Julien has gradually placed a lot of trust in her wisdom (indeed his apology was that he had failed to do so at first) and would do much to protect it, and her person. Both of them are acknowledging each other's consistency as it unfolds before them, and they're coming to regard it genuinely and even value it. This is btw while they're still consistently bickering and ducking from crossbow bolts and decimating poor familiars. Exceptional.