Retha was aware that something was wrong with the Caster of Cu Chulainn. That something was just off. But she wasn't sure what it specifically was. The feeling weighing on her like a heavy rock was in her stomach. But she chose to deal with the feeling in a neutral way. Instead of confronting Caster outright, she stayed with him and spent as much time with him as possible. Every Singularity, every confrontation, from training sessions in the simulator to destroying Demon Pillars. Retha kept Caster with her at all times.
The time that passed was dearly treasured to Retha. Orleans proved to have moments of comfort and contentment for their group. Caster Chulainn took the time to show Retha and Mash how to cook fresh fish over a campfire. With Retha eating it despite her distaste for fish. Something Mozart spilled the beans on near the end of the Singularity. Which had Caster Chulainn utterly perplexed yet highly amused. The druid teasing Retha for such with his fanged grin. Which had her blushing from ears to toes as she growled at Mozart for being a tattle tale. Yet both Casters simply laughed as Mash assured Retha that what she did was kind and sweet.
Septem proved to be a miserable trial of patience. With Retha barely holding to professional civility in the presence of Nero. Letting Mash do all the talking as Retha kept a hand in Caster Chulainn's to have a stiffened posture at all times. The only ones easing her out of that tenseness being Caster Chulainn or his Lancer counterpart. While traveling through Britannia tested everyone's nerves. A long night of temptation for both Hounds of Culann. So Retha told them both they were free to roam and not yake watch duty. Lancer taking the offer to kiss Retha before he sprinted off. Leaving Retha on a deep blush as Caster declined the offer. Choosing instead to sit with Retha and regail her with tales about the Fae as well as his comrades. One story about drunken fishing leaving them both in fits of laughter. Which had Retha snuggle close to Caster as they grinned and laughed. The next morning feeling much lighter than previous dawns. Lancer back at camp to look both happy and troubled. Yet Retha just kept both Hounds beside her. Telling them stories about her many ordeals going camping as a child. Which improves the mood even more.
It was during Okeanos that Retha finally figured it out. As she sat on the stairs leading up to the ship's wheel. Her eyes took in the sight of Caster Chulainn. His whole being so familiar and yet not. Retha was able to put words to it at last. So she got up to walk over and stand beside the druid. Letting the moment lengthen before she made her declaration. Telling Caster that he will always be Cu Chulainn. Even if he is so different than Lancer or Proto for that matter. That he is more than worthy of being the son of Lugh. She finalizes her point by making a pointed observation. How Caster has won a Holy Grail War when the others haven't. So if anyone needs to step up their game, it is the spearmen of his namesake.
Retha turns to give Caster a tight hug while he is too stunned to comment. But soon enough, the druid chuckles before hugging Retha back. Noting out loud that Retha is a wiser Master than he first assumed. The two enjoying the feeling of rightness that settles in. All while the waves gently sound out.