Archelaus probably wasn't the greatest choice for beginning any sort of reconnection into the world. So he wasn't a horrible individual but if it was a heart-to-heart, soppy, spill your sorrows sort of conversation that Arian was after she had most definitely come to the wrong person. It wasn't a lack of trust but somewhere down the line had become built into his personality, his mothers or brothers would likely have just as little success at trying to get him to open up about any sort of problem.
"I don't think they are." He chose to correct her upon that assumption. Looking at his own litter you had Archelaus who locked it all up, Vitus who barely said a word about anything, Bacchus may had said more but even he was pretty quiet and could you get Tiburtius to sit still for long enough for him to admit to any problems? To be fair Archie had never tried, they may have been a little more open but he still thought Arian was wrong on this matter.
She would offer to talk about anything else that he may have wanted to though truthfully he wasn't sure what to say. It wasn't that she was boring, he didn't know her after all he couldn't judge her that quickly and the number of scars and wounds upon her body she probably had some pretty action-packed stories, not that the idea of action inspired the boy either. "I don't know." He responded unhelpfully with a small shrug.