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She was willing to entrust her future to the Doctor. At several crucial moments, Kal'tsit chose to support the Doctor's decisions even when the outcome was uncertain. This demonstrated her growing trust.
She harbored many regrets. Kal'tsit had lived a long life and lost many people she knew. These experiences made it difficult for her to open her heart, including to the Doctor.
There's a sense of mutual understanding without many words. In some scenes, they work together perfectly without the need for lengthy explanations, as if they already understand each other's way of thinking.

Kal'tsit understands the Doctor more deeply than almost anyone else. Because they share such a long history, she knows sides of the Doctor that even other operators don't.
He rarely praised the Doctor directly. If the Doctor was successful, Kal'tsit usually only acknowledged the results briefly. However, when he entrusted the Doctor with an operation or a crucial decision, it was a sign of great trust.

Very protective, but doesn't express it directly. Kal'tsit repeatedly makes sure the Doctor doesn't get into too dangerous situations. She prefers to protect him through actions rather than words.
Honest and firm. If the Doctor makes a mistake or makes a decision she deems risky, Kal'tsit will tell her straight. She won't praise him just to please him.
Having high expectations, Kal'tsit knows the Doctor's abilities are extraordinary. Therefore, he often gives him significant responsibilities and expects the Doctor to make the best decisions.
Beginning to open up. At the beginning of the story, Kal'tsit kept almost all of her secrets about Terra and her past hidden. Gradually, she begins to share more with the Doctor, indicating her growing level of trust.
He considers the Doctor an irreplaceable companion. Despite their frequent disagreements, Kal'tsit admits that Rhodes Island's struggles would be much more difficult without the Doctor.
Sometimes, she shows her concern in her own unique way. For example, she reminds Doctor not to overexert himself, to get enough rest, and to maintain his physical condition. For Kal'tsit, concern is more often expressed through actions than gentle words.

Many fans describe their relationship as "trust rebuilt after a great loss." They are not a romantic couple in the official story, but two people who carry the burden of a long history and choose to work together for the future of Terra.
Kal'tsit and the Doctor's relationship is one of the most interesting dynamics in Arknights, filled with guilt, hope, and a slowly growing trust.

Cold and distant. After the Doctor lost his memory, Kal'tsit almost always spoke in a formal tone. He rarely showed emotion and was distrustful.
Still carrying the wounds of the past. Theresa's death and the fall of Babel left deep scars. Kal'tsit knew much about the Doctor's past, leading her to view him with suspicion and anger.
Still respecting the Doctor's abilities. Despite their strained relationship, Kal'tsit acknowledged the Doctor as an exceptional strategist. He continued to work with the Doctor for the safety of Rhodes Island and Terra.
Secretly caring. Kal'tsit often appears stern, but her actions show that she remains concerned about the Doctor's well-being. She ensures his well-being, gives him warnings when needed, and frequently entrusts him with important decisions.
Slowly, she begins to trust the Doctor again. As the story progresses, especially after various operations together, their relationship improves. Kal'tsit begins to see the current Doctor as a different person than the one he once was.