Kaldur watched as Artemis boarded the sub, worries about how she would fare bubbling in his mind, but as soon as the door sealed she seemed to relax; the tension he hadn't noticed in her shoulders unwinding, one hand reaching up to free her (newly) blood-red hair from its constriction, and she actually smiles. As he leads her towards Black Manta, she greets some of the crew by name. They (he, Nightwing, and Wally) had not planned on that (and who would), of course he remembered that she was the daughter of Sportsmaster, he had just not remembered that meant being friends with the children of his… business partners. Those she greets, greet back calling her 'little rose' and laughing at her apparent indignation at the continuation of such a nickname after so many years, and as she says, none of them are very little anymore, and he notices the sadness and fragility that sneaks into her eyes at this. And as they pass the medical wing, he ignores that her eyes gather a layer of mist and that he has to tug her hand (which he hadn't noticed he was holding) to remind her where they are and what they're attempting to do.
Her hand is soft and warm in his, something he knows he shouldn't be noticing (she has a boyfriend waiting for her, after all), she squeezes his hand in reassurance and he wonders if perhaps she should be more disguised than her hair, if she was the best choice for this assignment (but with her hand still in his, he can't manage to think of anyone better).
They meet Black Manta, Kaldur greets him with "Father" a half-smile and a nod (he's not quite sure his smile looks right, his face feels too tight, maybe his muscles had forgotten how) intending to introduce Diana formally. Artemis beats him to the punch, greeting Black Manta the same way she did as a child. "Uncle Manta!" was cried as she flung herself into his arms giggling like a mad-woman, startling Kaldur (he readied his water bearers, as subtly as he could, honestly expecting violence to break out).
"Well if it isn't my little rose-bud." Kaldur nearly choked on air at his father's voice, this was not the calm, cruel, methodical man he had come to see as the leader of this vessel; this was a loving man, a kind man, a father or husband or uncle or brother, not his father (although he would be lying to himself to say he had never seen this much softer side of the man behind the black mask).
For an instant he saw the chimera that was Artemis; her mother's kindness (he had made her acquaintance, as Calvin of course), her father's brutality (he was at a loss to see how anyone had missed it, she was viciously accurate with her arrows and always carried herself like an apex predator), her sisters refusal to bow to others (though if that was originally Artemis' he would never be completely sure), self-confidence instilled by her years of training (both mental as well as physical). Somehow all these pieces fit together and made up Artemis (his thoughts stutter as he valiantly tries to avoid thinking his Artemis) and all her complexities, and the many facets of her personality.
And as the ship sinks below the violent waters of the sea, he feels himself relax slightly, as if now, no one can take her from him (though he will only ever admit these selfish thoughts to himself). But he explains to her when she asks why he looks so content that the sea is his home, and to be completely surrounded by it (even if it is in a submarine that serves destruction and death more often than fresh seafood) is comforting. He knows she suspects he is lying, but she seems to brush it off (she knows he will tell her eventually, he always does) and continues (by his side) down the long, cold corridor. And with her hair (now much, much shorter) like a dancing flame, Kaldur wonders if he might be able to find his way out of this numbing darkness he has found himself submerged in (perhaps it descended with the sub, he never could tell), she would, after all, be a trustworthy guide.